diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8234e0ccb..d3b9ae016 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -116,7 +116,7 @@ jobs:
     strategy:
       fail-fast: true
       matrix:
-        os: [ubuntu-22.04]
+        os: [ubuntu-20.04]
         python-version: ${{ fromJSON(needs.select.outputs.cpython-versions) }}
         python-impl: [cpython]
         ytdl-test-set: ${{ fromJSON(needs.select.outputs.test-set) }}
@@ -133,12 +133,12 @@ jobs:
           ytdl-test-set: ${{ contains(needs.select.outputs.test-set, 'download') && 'download'  || 'nodownload' }}
           run-tests-ext: bat
         # jython
-        - os: ubuntu-22.04
+        - os: ubuntu-20.04
           python-version: 2.7
           python-impl: jython
           ytdl-test-set: ${{ contains(needs.select.outputs.test-set, 'core') && 'core' || 'nocore' }}
           run-tests-ext: sh
-        - os: ubuntu-22.04
+        - os: ubuntu-20.04
           python-version: 2.7
           python-impl: jython
           ytdl-test-set: ${{ contains(needs.select.outputs.test-set, 'download') && 'download'  || 'nodownload' }}
@@ -160,7 +160,7 @@ jobs:
       # NB may run apt-get install in Linux
       uses: ytdl-org/setup-python@v1
       env:
-        # Temporary (?) workaround for Python 3.5 failures - May 2024
+        # Temporary workaround for Python 3.5 failures - May 2024
         PIP_TRUSTED_HOST: "pypi.python.org pypi.org files.pythonhosted.org"
       with:
         python-version: ${{ matrix.python-version }}
@@ -240,10 +240,7 @@ jobs:
       # install 2.7
       shell: bash
       run: |
-        # Ubuntu 22.04 no longer has python-is-python2: fetch it
-        curl -L "http://launchpadlibrarian.net/474693132/python-is-python2_2.7.17-4_all.deb" -o python-is-python2.deb
-        sudo apt-get install -y python2
-        sudo dpkg --force-breaks -i python-is-python2.deb
+        sudo apt-get install -y python2 python-is-python2
         echo "PYTHONHOME=/usr" >> "$GITHUB_ENV"
     #-------- Python 2.6 --
     - name: Set up Python 2.6 environment
diff --git a/test/test_cache.py b/test/test_cache.py
index 0431f4f15..931074aa1 100644
--- a/test/test_cache.py
+++ b/test/test_cache.py
@@ -63,21 +63,9 @@ class TestCache(unittest.TestCase):
         obj = {'x': 1, 'y': ['ä', '\\a', True]}
         c.store('test_cache', 'k.', obj)
         self.assertEqual(c.load('test_cache', 'k.', min_ver='1970.01.01'), obj)
-        new_version = '.'.join(('%0.2d' % ((v + 1) if i == 0 else v, )) for i, v in enumerate(version_tuple(__version__)))
+        new_version = '.'.join(('%d' % ((v + 1) if i == 0 else v, )) for i, v in enumerate(version_tuple(__version__)))
         self.assertIs(c.load('test_cache', 'k.', min_ver=new_version), None)
 
-    def test_cache_clear(self):
-        ydl = FakeYDL({
-            'cachedir': self.test_dir,
-        })
-        c = Cache(ydl)
-        c.store('test_cache', 'k.', 'kay')
-        c.store('test_cache', 'l.', 'ell')
-        self.assertEqual(c.load('test_cache', 'k.'), 'kay')
-        c.clear('test_cache', 'k.')
-        self.assertEqual(c.load('test_cache', 'k.'), None)
-        self.assertEqual(c.load('test_cache', 'l.'), 'ell')
-
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/test/test_jsinterp.py b/test/test_jsinterp.py
index 479cb43a0..104e766be 100644
--- a/test/test_jsinterp.py
+++ b/test/test_jsinterp.py
@@ -1,5 +1,4 @@
 #!/usr/bin/env python
-# coding: utf-8
 
 from __future__ import unicode_literals
 
@@ -7,14 +6,12 @@ from __future__ import unicode_literals
 import os
 import sys
 import unittest
-
 sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 
 import math
 import re
-import time
 
-from youtube_dl.compat import compat_str as str
+from youtube_dl.compat import compat_str
 from youtube_dl.jsinterp import JS_Undefined, JSInterpreter
 
 NaN = object()
@@ -22,7 +19,7 @@ NaN = object()
 
 class TestJSInterpreter(unittest.TestCase):
     def _test(self, jsi_or_code, expected, func='f', args=()):
-        if isinstance(jsi_or_code, str):
+        if isinstance(jsi_or_code, compat_str):
             jsi_or_code = JSInterpreter(jsi_or_code)
         got = jsi_or_code.call_function(func, *args)
         if expected is NaN:
@@ -43,27 +40,16 @@ class TestJSInterpreter(unittest.TestCase):
         self._test('function f(){return 42 + 7;}', 49)
         self._test('function f(){return 42 + undefined;}', NaN)
         self._test('function f(){return 42 + null;}', 42)
-        self._test('function f(){return 1 + "";}', '1')
-        self._test('function f(){return 42 + "7";}', '427')
-        self._test('function f(){return false + true;}', 1)
-        self._test('function f(){return "false" + true;}', 'falsetrue')
-        self._test('function f(){return '
-                   '1 + "2" + [3,4] + {k: 56} + null + undefined + Infinity;}',
-                   '123,4[object Object]nullundefinedInfinity')
 
     def test_sub(self):
         self._test('function f(){return 42 - 7;}', 35)
         self._test('function f(){return 42 - undefined;}', NaN)
         self._test('function f(){return 42 - null;}', 42)
-        self._test('function f(){return 42 - "7";}', 35)
-        self._test('function f(){return 42 - "spam";}', NaN)
 
     def test_mul(self):
         self._test('function f(){return 42 * 7;}', 294)
         self._test('function f(){return 42 * undefined;}', NaN)
         self._test('function f(){return 42 * null;}', 0)
-        self._test('function f(){return 42 * "7";}', 294)
-        self._test('function f(){return 42 * "eggs";}', NaN)
 
     def test_div(self):
         jsi = JSInterpreter('function f(a, b){return a / b;}')
@@ -71,26 +57,17 @@ class TestJSInterpreter(unittest.TestCase):
         self._test(jsi, NaN, args=(JS_Undefined, 1))
         self._test(jsi, float('inf'), args=(2, 0))
         self._test(jsi, 0, args=(0, 3))
-        self._test(jsi, 6, args=(42, 7))
-        self._test(jsi, 0, args=(42, float('inf')))
-        self._test(jsi, 6, args=("42", 7))
-        self._test(jsi, NaN, args=("spam", 7))
 
     def test_mod(self):
         self._test('function f(){return 42 % 7;}', 0)
         self._test('function f(){return 42 % 0;}', NaN)
         self._test('function f(){return 42 % undefined;}', NaN)
-        self._test('function f(){return 42 % "7";}', 0)
-        self._test('function f(){return 42 % "beans";}', NaN)
 
     def test_exp(self):
         self._test('function f(){return 42 ** 2;}', 1764)
         self._test('function f(){return 42 ** undefined;}', NaN)
         self._test('function f(){return 42 ** null;}', 1)
-        self._test('function f(){return undefined ** 0;}', 1)
         self._test('function f(){return undefined ** 42;}', NaN)
-        self._test('function f(){return 42 ** "2";}', 1764)
-        self._test('function f(){return 42 ** "spam";}', NaN)
 
     def test_calc(self):
         self._test('function f(a){return 2*a+1;}', 7, args=[3])
@@ -112,60 +89,13 @@ class TestJSInterpreter(unittest.TestCase):
         self._test('function f(){return 19 & 21;}', 17)
         self._test('function f(){return 11 >> 2;}', 2)
         self._test('function f(){return []? 2+3: 4;}', 5)
-        # equality
-        self._test('function f(){return 1 == 1}', True)
-        self._test('function f(){return 1 == 1.0}', True)
-        self._test('function f(){return 1 == "1"}', True)
         self._test('function f(){return 1 == 2}', False)
-        self._test('function f(){return 1 != "1"}', False)
-        self._test('function f(){return 1 != 2}', True)
-        self._test('function f(){var x = {a: 1}; var y = x; return x == y}', True)
-        self._test('function f(){var x = {a: 1}; return x == {a: 1}}', False)
-        self._test('function f(){return NaN == NaN}', False)
-        self._test('function f(){return null == undefined}', True)
-        self._test('function f(){return "spam, eggs" == "spam, eggs"}', True)
-        # strict equality
-        self._test('function f(){return 1 === 1}', True)
-        self._test('function f(){return 1 === 1.0}', True)
-        self._test('function f(){return 1 === "1"}', False)
-        self._test('function f(){return 1 === 2}', False)
-        self._test('function f(){var x = {a: 1}; var y = x; return x === y}', True)
-        self._test('function f(){var x = {a: 1}; return x === {a: 1}}', False)
-        self._test('function f(){return NaN === NaN}', False)
-        self._test('function f(){return null === undefined}', False)
-        self._test('function f(){return null === null}', True)
-        self._test('function f(){return undefined === undefined}', True)
-        self._test('function f(){return "uninterned" === "uninterned"}', True)
-        self._test('function f(){return 1 === 1}', True)
-        self._test('function f(){return 1 === "1"}', False)
-        self._test('function f(){return 1 !== 1}', False)
-        self._test('function f(){return 1 !== "1"}', True)
-        # expressions
         self._test('function f(){return 0 && 1 || 2;}', 2)
         self._test('function f(){return 0 ?? 42;}', 0)
         self._test('function f(){return "life, the universe and everything" < 42;}', False)
         # https://github.com/ytdl-org/youtube-dl/issues/32815
         self._test('function f(){return 0  - 7 * - 6;}', 42)
 
-    def test_bitwise_operators_typecast(self):
-        # madness
-        self._test('function f(){return null << 5}', 0)
-        self._test('function f(){return undefined >> 5}', 0)
-        self._test('function f(){return 42 << NaN}', 42)
-        self._test('function f(){return 42 << Infinity}', 42)
-        self._test('function f(){return 0.0 << null}', 0)
-        self._test('function f(){return NaN << 42}', 0)
-        self._test('function f(){return "21.9" << 1}', 42)
-        self._test('function f(){return true << "5";}', 32)
-        self._test('function f(){return true << true;}', 2)
-        self._test('function f(){return "19" & "21.9";}', 17)
-        self._test('function f(){return "19" & false;}', 0)
-        self._test('function f(){return "11.0" >> "2.1";}', 2)
-        self._test('function f(){return 5 ^ 9;}', 12)
-        self._test('function f(){return 0.0 << NaN}', 0)
-        self._test('function f(){return null << undefined}', 0)
-        self._test('function f(){return 21 << 4294967297}', 42)
-
     def test_array_access(self):
         self._test('function f(){var x = [1,2,3]; x[0] = 4; x[0] = 5; x[2.0] = 7; return x;}', [5, 2, 7])
 
@@ -180,8 +110,8 @@ class TestJSInterpreter(unittest.TestCase):
         self._test('function f(){var x = 20; x = 30 + 1; return x;}', 31)
         self._test('function f(){var x = 20; x += 30 + 1; return x;}', 51)
         self._test('function f(){var x = 20; x -= 30 + 1; return x;}', -11)
-        self._test('function f(){var x = 2; var y = ["a", "b"]; y[x%y["length"]]="z"; return y}', ['z', 'b'])
 
+    @unittest.skip('Not yet fully implemented')
     def test_comments(self):
         self._test('''
             function f() {
@@ -200,15 +130,6 @@ class TestJSInterpreter(unittest.TestCase):
             }
         ''', 3)
 
-        self._test('''
-            function f() {
-                var x = ( /* 1 + */ 2 +
-                          /* 30 * 40 */
-                          50);
-                return x;
-            }
-        ''', 52)
-
     def test_precedence(self):
         self._test('''
             function f() {
@@ -230,34 +151,6 @@ class TestJSInterpreter(unittest.TestCase):
         self._test(jsi, 86000, args=['12/31/1969 18:01:26 MDT'])
         # epoch 0
         self._test(jsi, 0, args=['1 January 1970 00:00:00 UTC'])
-        # undefined
-        self._test(jsi, NaN, args=[JS_Undefined])
-        # y,m,d, ... - may fail with older dates lacking DST data
-        jsi = JSInterpreter(
-            'function f() { return new Date(%s); }'
-            % ('2024, 5, 29, 2, 52, 12, 42',))
-        self._test(jsi, (
-            1719625932042                           # UK value
-            + (
-                + 3600                              # back to GMT
-                + (time.altzone if time.daylight    # host's DST
-                   else time.timezone)
-            ) * 1000))
-        # no arg
-        self.assertAlmostEqual(JSInterpreter(
-            'function f() { return new Date() - 0; }').call_function('f'),
-            time.time() * 1000, delta=100)
-        # Date.now()
-        self.assertAlmostEqual(JSInterpreter(
-            'function f() { return Date.now(); }').call_function('f'),
-            time.time() * 1000, delta=100)
-        # Date.parse()
-        jsi = JSInterpreter('function f(dt) { return Date.parse(dt); }')
-        self._test(jsi, 0, args=['1 January 1970 00:00:00 UTC'])
-        # Date.UTC()
-        jsi = JSInterpreter('function f() { return Date.UTC(%s); }'
-                            % ('1970, 0, 1, 0, 0, 0, 0',))
-        self._test(jsi, 0)
 
     def test_call(self):
         jsi = JSInterpreter('''
@@ -372,28 +265,8 @@ class TestJSInterpreter(unittest.TestCase):
         self._test('function f() { a=5; return (a -= 1, a+=3, a); }', 7)
         self._test('function f() { return (l=[0,1,2,3], function(a, b){return a+b})((l[1], l[2]), l[3]) }', 5)
 
-    def test_not(self):
-        self._test('function f() { return ! undefined; }', True)
-        self._test('function f() { return !0; }', True)
-        self._test('function f() { return !!0; }', False)
-        self._test('function f() { return ![]; }', False)
-        self._test('function f() { return !0 !== false; }', True)
-
     def test_void(self):
-        self._test('function f() { return void 42; }', JS_Undefined)
-
-    def test_typeof(self):
-        self._test('function f() { return typeof undefined; }', 'undefined')
-        self._test('function f() { return typeof NaN; }', 'number')
-        self._test('function f() { return typeof Infinity; }', 'number')
-        self._test('function f() { return typeof true; }', 'boolean')
-        self._test('function f() { return typeof null; }', 'object')
-        self._test('function f() { return typeof "a string"; }', 'string')
-        self._test('function f() { return typeof 42; }', 'number')
-        self._test('function f() { return typeof 42.42; }', 'number')
-        self._test('function f() { var g = function(){}; return typeof g; }', 'function')
-        self._test('function f() { return typeof {key: "value"}; }', 'object')
-        # not yet implemented: Symbol, BigInt
+        self._test('function f() { return void 42; }', None)
 
     def test_return_function(self):
         jsi = JSInterpreter('''
@@ -410,7 +283,7 @@ class TestJSInterpreter(unittest.TestCase):
     def test_undefined(self):
         self._test('function f() { return undefined === undefined; }', True)
         self._test('function f() { return undefined; }', JS_Undefined)
-        self._test('function f() { return undefined ?? 42; }', 42)
+        self._test('function f() {return undefined ?? 42; }', 42)
         self._test('function f() { let v; return v; }', JS_Undefined)
         self._test('function f() { let v; return v**0; }', 1)
         self._test('function f() { let v; return [v>42, v<=42, v&&42, 42&&v]; }',
@@ -451,19 +324,8 @@ class TestJSInterpreter(unittest.TestCase):
         self._test('function f() { let a; return a?.qq; }', JS_Undefined)
         self._test('function f() { let a = {m1: 42, m2: 0 }; return a?.qq; }', JS_Undefined)
 
-    def test_indexing(self):
-        self._test('function f() { return [1, 2, 3, 4][3]}', 4)
-        self._test('function f() { return [1, [2, [3, [4]]]][1][1][1][0]}', 4)
-        self._test('function f() { var o = {1: 2, 3: 4}; return o[3]}', 4)
-        self._test('function f() { var o = {1: 2, 3: 4}; return o["3"]}', 4)
-        self._test('function f() { return [1, [2, {3: [4]}]][1][1]["3"][0]}', 4)
-        self._test('function f() { return [1, 2, 3, 4].length}', 4)
-        self._test('function f() { var o = {1: 2, 3: 4}; return o.length}', JS_Undefined)
-        self._test('function f() { var o = {1: 2, 3: 4}; o["length"] = 42; return o.length}', 42)
-
     def test_regex(self):
         self._test('function f() { let a=/,,[/,913,/](,)}/; }', None)
-        self._test('function f() { let a=/,,[/,913,/](,)}/; return a.source;  }', ',,[/,913,/](,)}')
 
         jsi = JSInterpreter('''
             function x() { let a=/,,[/,913,/](,)}/; "".replace(a, ""); return a; }
@@ -511,6 +373,13 @@ class TestJSInterpreter(unittest.TestCase):
         self._test('function f(){return -524999584 << 5}', 379882496)
         self._test('function f(){return 1236566549 << 5}', 915423904)
 
+    def test_bitwise_operators_typecast(self):
+        # madness
+        self._test('function f(){return null << 5}', 0)
+        self._test('function f(){return undefined >> 5}', 0)
+        self._test('function f(){return 42 << NaN}', 42)
+        self._test('function f(){return 42 << Infinity}', 42)
+
     def test_negative(self):
         self._test('function f(){return 2    *    -2.0    ;}', -4)
         self._test('function f(){return 2    -    - -2    ;}', 0)
@@ -542,19 +411,10 @@ class TestJSInterpreter(unittest.TestCase):
             self._test(jsi, 't-e-s-t', args=[test_input, '-'])
             self._test(jsi, '', args=[[], '-'])
 
-        self._test('function f(){return '
-                   '[1, 1.0, "abc", {a: 1}, null, undefined, Infinity, NaN].join()}',
-                   '1,1,abc,[object Object],,,Infinity,NaN')
-        self._test('function f(){return '
-                   '[1, 1.0, "abc", {a: 1}, null, undefined, Infinity, NaN].join("~")}',
-                   '1~1~abc~[object Object]~~~Infinity~NaN')
-
     def test_split(self):
         test_result = list('test')
         tests = [
             'function f(a, b){return a.split(b)}',
-            'function f(a, b){return a["split"](b)}',
-            'function f(a, b){let x = ["split"]; return a[x[0]](b)}',
             'function f(a, b){return String.prototype.split.call(a, b)}',
             'function f(a, b){return String.prototype.split.apply(a, [b])}',
         ]
@@ -564,93 +424,6 @@ class TestJSInterpreter(unittest.TestCase):
             self._test(jsi, test_result, args=['t-e-s-t', '-'])
             self._test(jsi, [''], args=['', '-'])
             self._test(jsi, [], args=['', ''])
-        # RegExp split
-        self._test('function f(){return "test".split(/(?:)/)}',
-                   ['t', 'e', 's', 't'])
-        self._test('function f(){return "t-e-s-t".split(/[es-]+/)}',
-                   ['t', 't'])
-        # from MDN: surrogate pairs aren't handled: case 1 fails
-        # self._test('function f(){return "😄😄".split(/(?:)/)}',
-        #            ['\ud83d', '\ude04', '\ud83d', '\ude04'])
-        # case 2 beats Py3.2: it gets the case 1 result
-        if sys.version_info >= (2, 6) and not ((3, 0) <= sys.version_info < (3, 3)):
-            self._test('function f(){return "😄😄".split(/(?:)/u)}',
-                       ['😄', '😄'])
-
-    def test_slice(self):
-        self._test('function f(){return [0, 1, 2, 3, 4, 5, 6, 7, 8].slice()}', [0, 1, 2, 3, 4, 5, 6, 7, 8])
-        self._test('function f(){return [0, 1, 2, 3, 4, 5, 6, 7, 8].slice(0)}', [0, 1, 2, 3, 4, 5, 6, 7, 8])
-        self._test('function f(){return [0, 1, 2, 3, 4, 5, 6, 7, 8].slice(5)}', [5, 6, 7, 8])
-        self._test('function f(){return [0, 1, 2, 3, 4, 5, 6, 7, 8].slice(99)}', [])
-        self._test('function f(){return [0, 1, 2, 3, 4, 5, 6, 7, 8].slice(-2)}', [7, 8])
-        self._test('function f(){return [0, 1, 2, 3, 4, 5, 6, 7, 8].slice(-99)}', [0, 1, 2, 3, 4, 5, 6, 7, 8])
-        self._test('function f(){return [0, 1, 2, 3, 4, 5, 6, 7, 8].slice(0, 0)}', [])
-        self._test('function f(){return [0, 1, 2, 3, 4, 5, 6, 7, 8].slice(1, 0)}', [])
-        self._test('function f(){return [0, 1, 2, 3, 4, 5, 6, 7, 8].slice(0, 1)}', [0])
-        self._test('function f(){return [0, 1, 2, 3, 4, 5, 6, 7, 8].slice(3, 6)}', [3, 4, 5])
-        self._test('function f(){return [0, 1, 2, 3, 4, 5, 6, 7, 8].slice(1, -1)}', [1, 2, 3, 4, 5, 6, 7])
-        self._test('function f(){return [0, 1, 2, 3, 4, 5, 6, 7, 8].slice(-1, 1)}', [])
-        self._test('function f(){return [0, 1, 2, 3, 4, 5, 6, 7, 8].slice(-3, -1)}', [6, 7])
-        self._test('function f(){return "012345678".slice()}', '012345678')
-        self._test('function f(){return "012345678".slice(0)}', '012345678')
-        self._test('function f(){return "012345678".slice(5)}', '5678')
-        self._test('function f(){return "012345678".slice(99)}', '')
-        self._test('function f(){return "012345678".slice(-2)}', '78')
-        self._test('function f(){return "012345678".slice(-99)}', '012345678')
-        self._test('function f(){return "012345678".slice(0, 0)}', '')
-        self._test('function f(){return "012345678".slice(1, 0)}', '')
-        self._test('function f(){return "012345678".slice(0, 1)}', '0')
-        self._test('function f(){return "012345678".slice(3, 6)}', '345')
-        self._test('function f(){return "012345678".slice(1, -1)}', '1234567')
-        self._test('function f(){return "012345678".slice(-1, 1)}', '')
-        self._test('function f(){return "012345678".slice(-3, -1)}', '67')
-
-    def test_splice(self):
-        self._test('function f(){var T = ["0", "1", "2"]; T["splice"](2, 1, "0")[0]; return T }', ['0', '1', '0'])
-
-    def test_pop(self):
-        # pop
-        self._test('function f(){var a = [0, 1, 2, 3, 4, 5, 6, 7, 8]; return [a.pop(), a]}',
-                   [8, [0, 1, 2, 3, 4, 5, 6, 7]])
-        self._test('function f(){return [].pop()}', JS_Undefined)
-        # push
-        self._test('function f(){var a = [0, 1, 2]; return [a.push(3, 4), a]}',
-                   [5, [0, 1, 2, 3, 4]])
-        self._test('function f(){var a = [0, 1, 2]; return [a.push(), a]}',
-                   [3, [0, 1, 2]])
-
-    def test_shift(self):
-        # shift
-        self._test('function f(){var a = [0, 1, 2, 3, 4, 5, 6, 7, 8]; return [a.shift(), a]}',
-                   [0, [1, 2, 3, 4, 5, 6, 7, 8]])
-        self._test('function f(){return [].shift()}', JS_Undefined)
-        # unshift
-        self._test('function f(){var a = [0, 1, 2]; return [a.unshift(3, 4), a]}',
-                   [5, [3, 4, 0, 1, 2]])
-        self._test('function f(){var a = [0, 1, 2]; return [a.unshift(), a]}',
-                   [3, [0, 1, 2]])
-
-    def test_forEach(self):
-        self._test('function f(){var ret = []; var l = [4, 2]; '
-                   'var log = function(e,i,a){ret.push([e,i,a]);}; '
-                   'l.forEach(log); '
-                   'return [ret.length, ret[0][0], ret[1][1], ret[0][2]]}',
-                   [2, 4, 1, [4, 2]])
-        self._test('function f(){var ret = []; var l = [4, 2]; '
-                   'var log = function(e,i,a){this.push([e,i,a]);}; '
-                   'l.forEach(log, ret); '
-                   'return [ret.length, ret[0][0], ret[1][1], ret[0][2]]}',
-                   [2, 4, 1, [4, 2]])
-
-    def test_extract_function(self):
-        jsi = JSInterpreter('function a(b) { return b + 1; }')
-        func = jsi.extract_function('a')
-        self.assertEqual(func([2]), 3)
-
-    def test_extract_function_with_global_stack(self):
-        jsi = JSInterpreter('function c(d) { return d + e + f + g; }')
-        func = jsi.extract_function('c', {'e': 10}, {'f': 100, 'g': 1000})
-        self.assertEqual(func([1]), 1111)
 
 
 if __name__ == '__main__':
diff --git a/test/test_youtube_signature.py b/test/test_youtube_signature.py
index 98221b9c2..cc18d0f7b 100644
--- a/test/test_youtube_signature.py
+++ b/test/test_youtube_signature.py
@@ -1,5 +1,4 @@
 #!/usr/bin/env python
-# coding: utf-8
 
 from __future__ import unicode_literals
 
@@ -13,7 +12,6 @@ import re
 import string
 
 from youtube_dl.compat import (
-    compat_contextlib_suppress,
     compat_open as open,
     compat_str,
     compat_urlretrieve,
@@ -52,93 +50,23 @@ _SIG_TESTS = [
     (
         'https://s.ytimg.com/yts/jsbin/html5player-en_US-vflBb0OQx.js',
         84,
-        '123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQ0STUVWXYZ!"#$%&\'()*+,@./:;<=>',
+        '123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQ0STUVWXYZ!"#$%&\'()*+,@./:;<=>'
     ),
     (
         'https://s.ytimg.com/yts/jsbin/html5player-en_US-vfl9FYC6l.js',
         83,
-        '123456789abcdefghijklmnopqr0tuvwxyzABCDETGHIJKLMNOPQRS>UVWXYZ!"#$%&\'()*+,-./:;<=F',
+        '123456789abcdefghijklmnopqr0tuvwxyzABCDETGHIJKLMNOPQRS>UVWXYZ!"#$%&\'()*+,-./:;<=F'
     ),
     (
         'https://s.ytimg.com/yts/jsbin/html5player-en_US-vflCGk6yw/html5player.js',
         '4646B5181C6C3020DF1D9C7FCFEA.AD80ABF70C39BD369CCCAE780AFBB98FA6B6CB42766249D9488C288',
-        '82C8849D94266724DC6B6AF89BBFA087EACCD963.B93C07FBA084ACAEFCF7C9D1FD0203C6C1815B6B',
+        '82C8849D94266724DC6B6AF89BBFA087EACCD963.B93C07FBA084ACAEFCF7C9D1FD0203C6C1815B6B'
     ),
     (
         'https://s.ytimg.com/yts/jsbin/html5player-en_US-vflKjOTVq/html5player.js',
         '312AA52209E3623129A412D56A40F11CB0AF14AE.3EE09501CB14E3BCDC3B2AE808BF3F1D14E7FBF12',
         '112AA5220913623229A412D56A40F11CB0AF14AE.3EE0950FCB14EEBCDC3B2AE808BF331D14E7FBF3',
-    ),
-    (
-        'https://www.youtube.com/s/player/6ed0d907/player_ias.vflset/en_US/base.js',
-        '2aq0aqSyOoJXtK73m-uME_jv7-pT15gOFC02RFkGMqWpzEICs69VdbwQ0LDp1v7j8xx92efCJlYFYb1sUkkBSPOlPmXgIARw8JQ0qOAOAA',
-        'AOq0QJ8wRAIgXmPlOPSBkkUs1bYFYlJCfe29xx8j7v1pDL2QwbdV96sCIEzpWqMGkFR20CFOg51Tp-7vj_EMu-m37KtXJoOySqa0',
-    ),
-    (
-        'https://www.youtube.com/s/player/3bb1f723/player_ias.vflset/en_US/base.js',
-        '2aq0aqSyOoJXtK73m-uME_jv7-pT15gOFC02RFkGMqWpzEICs69VdbwQ0LDp1v7j8xx92efCJlYFYb1sUkkBSPOlPmXgIARw8JQ0qOAOAA',
-        'MyOSJXtKI3m-uME_jv7-pT12gOFC02RFkGoqWpzE0Cs69VdbwQ0LDp1v7j8xx92efCJlYFYb1sUkkBSPOlPmXgIARw8JQ0qOAOAA',
-    ),
-    (
-        'https://www.youtube.com/s/player/2f1832d2/player_ias.vflset/en_US/base.js',
-        '2aq0aqSyOoJXtK73m-uME_jv7-pT15gOFC02RFkGMqWpzEICs69VdbwQ0LDp1v7j8xx92efCJlYFYb1sUkkBSPOlPmXgIARw8JQ0qOAOAA',
-        '0QJ8wRAIgXmPlOPSBkkUs1bYFYlJCfe29xxAj7v1pDL0QwbdV96sCIEzpWqMGkFR20CFOg51Tp-7vj_EMu-m37KtXJ2OySqa0q',
-    ),
-    (
-        'https://www.youtube.com/s/player/643afba4/tv-player-ias.vflset/tv-player-ias.js',
-        '2aq0aqSyOoJXtK73m-uME_jv7-pT15gOFC02RFkGMqWpzEICs69VdbwQ0LDp1v7j8xx92efCJlYFYb1sUkkBSPOlPmXgIARw8JQ0qOAOAA',
-        'AAOAOq0QJ8wRAIgXmPlOPSBkkUs1bYFYlJCfe29xx8j7vgpDL0QwbdV06sCIEzpWqMGkFR20CFOS21Tp-7vj_EMu-m37KtXJoOy1',
-    ),
-    (
-        'https://www.youtube.com/s/player/363db69b/player_ias.vflset/en_US/base.js',
-        '2aq0aqSyOoJXtK73m-uME_jv7-pT15gOFC02RFkGMqWpzEICs69VdbwQ0LDp1v7j8xx92efCJlYFYb1sUkkBSPOlPmXgIARw8JQ0qOAOAA',
-        '0aqSyOoJXtK73m-uME_jv7-pT15gOFC02RFkGMqWpz2ICs6EVdbwQ0LDp1v7j8xx92efCJlYFYb1sUkkBSPOlPmXgIARw8JQ0qOAOAA',
-    ),
-    (
-        'https://www.youtube.com/s/player/363db69b/player_ias_tce.vflset/en_US/base.js',
-        '2aq0aqSyOoJXtK73m-uME_jv7-pT15gOFC02RFkGMqWpzEICs69VdbwQ0LDp1v7j8xx92efCJlYFYb1sUkkBSPOlPmXgIARw8JQ0qOAOAA',
-        '0aqSyOoJXtK73m-uME_jv7-pT15gOFC02RFkGMqWpz2ICs6EVdbwQ0LDp1v7j8xx92efCJlYFYb1sUkkBSPOlPmXgIARw8JQ0qOAOAA',
-    ),
-    (
-        'https://www.youtube.com/s/player/4fcd6e4a/player_ias.vflset/en_US/base.js',
-        '2aq0aqSyOoJXtK73m-uME_jv7-pT15gOFC02RFkGMqWpzEICs69VdbwQ0LDp1v7j8xx92efCJlYFYb1sUkkBSPOlPmXgIARw8JQ0qOAOAA',
-        'wAOAOq0QJ8ARAIgXmPlOPSBkkUs1bYFYlJCfe29xx8q7v1pDL0QwbdV96sCIEzpWqMGkFR20CFOg51Tp-7vj_EMu-m37KtXJoOySqa0',
-    ),
-    (
-        'https://www.youtube.com/s/player/4fcd6e4a/player_ias_tce.vflset/en_US/base.js',
-        '2aq0aqSyOoJXtK73m-uME_jv7-pT15gOFC02RFkGMqWpzEICs69VdbwQ0LDp1v7j8xx92efCJlYFYb1sUkkBSPOlPmXgIARw8JQ0qOAOAA',
-        'wAOAOq0QJ8ARAIgXmPlOPSBkkUs1bYFYlJCfe29xx8q7v1pDL0QwbdV96sCIEzpWqMGkFR20CFOg51Tp-7vj_EMu-m37KtXJoOySqa0',
-    ),
-    (
-        'https://www.youtube.com/s/player/20830619/player_ias.vflset/en_US/base.js',
-        '2aq0aqSyOoJXtK73m-uME_jv7-pT15gOFC02RFkGMqWpzEICs69VdbwQ0LDp1v7j8xx92efCJlYFYb1sUkkBSPOlPmXgIARw8JQ0qOAOAA',
-        '7AOq0QJ8wRAIgXmPlOPSBkkAs1bYFYlJCfe29xx8jOv1pDL0Q2bdV96sCIEzpWqMGkFR20CFOg51Tp-7vj_EMu-m37KtXJoOySqa0qaw',
-    ),
-    (
-        'https://www.youtube.com/s/player/20830619/player_ias_tce.vflset/en_US/base.js',
-        '2aq0aqSyOoJXtK73m-uME_jv7-pT15gOFC02RFkGMqWpzEICs69VdbwQ0LDp1v7j8xx92efCJlYFYb1sUkkBSPOlPmXgIARw8JQ0qOAOAA',
-        '7AOq0QJ8wRAIgXmPlOPSBkkAs1bYFYlJCfe29xx8jOv1pDL0Q2bdV96sCIEzpWqMGkFR20CFOg51Tp-7vj_EMu-m37KtXJoOySqa0qaw',
-    ),
-    (
-        'https://www.youtube.com/s/player/20830619/player-plasma-ias-phone-en_US.vflset/base.js',
-        '2aq0aqSyOoJXtK73m-uME_jv7-pT15gOFC02RFkGMqWpzEICs69VdbwQ0LDp1v7j8xx92efCJlYFYb1sUkkBSPOlPmXgIARw8JQ0qOAOAA',
-        '7AOq0QJ8wRAIgXmPlOPSBkkAs1bYFYlJCfe29xx8jOv1pDL0Q2bdV96sCIEzpWqMGkFR20CFOg51Tp-7vj_EMu-m37KtXJoOySqa0qaw',
-    ),
-    (
-        'https://www.youtube.com/s/player/20830619/player-plasma-ias-tablet-en_US.vflset/base.js',
-        '2aq0aqSyOoJXtK73m-uME_jv7-pT15gOFC02RFkGMqWpzEICs69VdbwQ0LDp1v7j8xx92efCJlYFYb1sUkkBSPOlPmXgIARw8JQ0qOAOAA',
-        '7AOq0QJ8wRAIgXmPlOPSBkkAs1bYFYlJCfe29xx8jOv1pDL0Q2bdV96sCIEzpWqMGkFR20CFOg51Tp-7vj_EMu-m37KtXJoOySqa0qaw',
-    ),
-    (
-        'https://www.youtube.com/s/player/8a8ac953/player_ias_tce.vflset/en_US/base.js',
-        '2aq0aqSyOoJXtK73m-uME_jv7-pT15gOFC02RFkGMqWpzEICs69VdbwQ0LDp1v7j8xx92efCJlYFYb1sUkkBSPOlPmXgIARw8JQ0qOAOAA',
-        'IAOAOq0QJ8wRAAgXmPlOPSBkkUs1bYFYlJCfe29xx8j7v1pDL0QwbdV96sCIEzpWqMGkFR20CFOg51Tp-7vj_E2u-m37KtXJoOySqa0',
-    ),
-    (
-        'https://www.youtube.com/s/player/8a8ac953/tv-player-es6.vflset/tv-player-es6.js',
-        '2aq0aqSyOoJXtK73m-uME_jv7-pT15gOFC02RFkGMqWpzEICs69VdbwQ0LDp1v7j8xx92efCJlYFYb1sUkkBSPOlPmXgIARw8JQ0qOAOAA',
-        'IAOAOq0QJ8wRAAgXmPlOPSBkkUs1bYFYlJCfe29xx8j7v1pDL0QwbdV96sCIEzpWqMGkFR20CFOg51Tp-7vj_E2u-m37KtXJoOySqa0',
-    ),
+    )
 ]
 
 _NSIG_TESTS = [
@@ -208,16 +136,12 @@ _NSIG_TESTS = [
     ),
     (
         'https://www.youtube.com/s/player/c57c113c/player_ias.vflset/en_US/base.js',
-        'M92UUMHa8PdvPd3wyM', '3hPqLJsiNZx7yA',
+        '-Txvy6bT5R6LqgnQNx', 'dcklJCnRUHbgSg',
     ),
     (
         'https://www.youtube.com/s/player/5a3b6271/player_ias.vflset/en_US/base.js',
         'B2j7f_UPT4rfje85Lu_e', 'm5DmNymaGQ5RdQ',
     ),
-    (
-        'https://www.youtube.com/s/player/7a062b77/player_ias.vflset/en_US/base.js',
-        'NRcE3y3mVtm_cV-W', 'VbsCYUATvqlt5w',
-    ),
     (
         'https://www.youtube.com/s/player/dac945fd/player_ias.vflset/en_US/base.js',
         'o8BkRxXhuYsBCWi6RplPdP', '3Lx32v_hmzTm6A',
@@ -228,11 +152,7 @@ _NSIG_TESTS = [
     ),
     (
         'https://www.youtube.com/s/player/cfa9e7cb/player_ias.vflset/en_US/base.js',
-        'aCi3iElgd2kq0bxVbQ', 'QX1y8jGb2IbZ0w',
-    ),
-    (
-        'https://www.youtube.com/s/player/8c7583ff/player_ias.vflset/en_US/base.js',
-        '1wWCVpRR96eAmMI87L', 'KSkWAVv1ZQxC3A',
+        'qO0NiMtYQ7TeJnfFG2', 'k9cuJDHNS5O7kQ',
     ),
     (
         'https://www.youtube.com/s/player/b7910ca8/player_ias.vflset/en_US/base.js',
@@ -246,110 +166,6 @@ _NSIG_TESTS = [
         'https://www.youtube.com/s/player/b22ef6e7/player_ias.vflset/en_US/base.js',
         'b6HcntHGkvBLk_FRf', 'kNPW6A7FyP2l8A',
     ),
-    (
-        'https://www.youtube.com/s/player/3400486c/player_ias.vflset/en_US/base.js',
-        'lL46g3XifCKUZn1Xfw', 'z767lhet6V2Skl',
-    ),
-    (
-        'https://www.youtube.com/s/player/5604538d/player_ias.vflset/en_US/base.js',
-        '7X-he4jjvMx7BCX', 'sViSydX8IHtdWA',
-    ),
-    (
-        'https://www.youtube.com/s/player/20dfca59/player_ias.vflset/en_US/base.js',
-        '-fLCxedkAk4LUTK2', 'O8kfRq1y1eyHGw',
-    ),
-    (
-        'https://www.youtube.com/s/player/b12cc44b/player_ias.vflset/en_US/base.js',
-        'keLa5R2U00sR9SQK', 'N1OGyujjEwMnLw',
-    ),
-    (
-        'https://www.youtube.com/s/player/3bb1f723/player_ias.vflset/en_US/base.js',
-        'gK15nzVyaXE9RsMP3z', 'ZFFWFLPWx9DEgQ',
-    ),
-    (
-        'https://www.youtube.com/s/player/f8f53e1a/player_ias.vflset/en_US/base.js',
-        'VTQOUOv0mCIeJ7i8kZB', 'kcfD8wy0sNLyNQ',
-    ),
-    (
-        'https://www.youtube.com/s/player/2f1832d2/player_ias.vflset/en_US/base.js',
-        'YWt1qdbe8SAfkoPHW5d', 'RrRjWQOJmBiP',
-    ),
-    (
-        'https://www.youtube.com/s/player/9c6dfc4a/player_ias.vflset/en_US/base.js',
-        'jbu7ylIosQHyJyJV', 'uwI0ESiynAmhNg',
-    ),
-    (
-        'https://www.youtube.com/s/player/f6e09c70/player_ias.vflset/en_US/base.js',
-        'W9HJZKktxuYoDTqW', 'jHbbkcaxm54',
-    ),
-    (
-        'https://www.youtube.com/s/player/f6e09c70/player_ias_tce.vflset/en_US/base.js',
-        'W9HJZKktxuYoDTqW', 'jHbbkcaxm54',
-    ),
-    (
-        'https://www.youtube.com/s/player/e7567ecf/player_ias_tce.vflset/en_US/base.js',
-        'Sy4aDGc0VpYRR9ew_', '5UPOT1VhoZxNLQ',
-    ),
-    (
-        'https://www.youtube.com/s/player/d50f54ef/player_ias_tce.vflset/en_US/base.js',
-        'Ha7507LzRmH3Utygtj', 'XFTb2HoeOE5MHg',
-    ),
-    (
-        'https://www.youtube.com/s/player/074a8365/player_ias_tce.vflset/en_US/base.js',
-        'Ha7507LzRmH3Utygtj', 'ufTsrE0IVYrkl8v',
-    ),
-    (
-        'https://www.youtube.com/s/player/643afba4/player_ias.vflset/en_US/base.js',
-        'N5uAlLqm0eg1GyHO', 'dCBQOejdq5s-ww',
-    ),
-    (
-        'https://www.youtube.com/s/player/69f581a5/tv-player-ias.vflset/tv-player-ias.js',
-        '-qIP447rVlTTwaZjY', 'KNcGOksBAvwqQg',
-    ),
-    (
-        'https://www.youtube.com/s/player/643afba4/tv-player-ias.vflset/tv-player-ias.js',
-        'ir9-V6cdbCiyKxhr', '2PL7ZDYAALMfmA',
-    ),
-    (
-        'https://www.youtube.com/s/player/643afba4/player_ias.vflset/en_US/base.js',
-        'ir9-V6cdbCiyKxhr', '2PL7ZDYAALMfmA',
-    ),
-    (
-        'https://www.youtube.com/s/player/363db69b/player_ias.vflset/en_US/base.js',
-        'eWYu5d5YeY_4LyEDc', 'XJQqf-N7Xra3gg',
-    ),
-    (
-        'https://www.youtube.com/s/player/4fcd6e4a/player_ias.vflset/en_US/base.js',
-        'o_L251jm8yhZkWtBW', 'lXoxI3XvToqn6A',
-    ),
-    (
-        'https://www.youtube.com/s/player/4fcd6e4a/tv-player-ias.vflset/tv-player-ias.js',
-        'o_L251jm8yhZkWtBW', 'lXoxI3XvToqn6A',
-    ),
-    (
-        'https://www.youtube.com/s/player/20830619/tv-player-ias.vflset/tv-player-ias.js',
-        'ir9-V6cdbCiyKxhr', '9YE85kNjZiS4',
-    ),
-    (
-        'https://www.youtube.com/s/player/20830619/player-plasma-ias-phone-en_US.vflset/base.js',
-        'ir9-V6cdbCiyKxhr', '9YE85kNjZiS4',
-    ),
-    (
-        'https://www.youtube.com/s/player/20830619/player-plasma-ias-tablet-en_US.vflset/base.js',
-        'ir9-V6cdbCiyKxhr', '9YE85kNjZiS4',
-    ),
-    (
-        'https://www.youtube.com/s/player/8a8ac953/player_ias_tce.vflset/en_US/base.js',
-        'MiBYeXx_vRREbiCCmh', 'RtZYMVvmkE0JE',
-    ),
-    (
-        'https://www.youtube.com/s/player/8a8ac953/tv-player-es6.vflset/tv-player-es6.js',
-        'MiBYeXx_vRREbiCCmh', 'RtZYMVvmkE0JE',
-    ),
-    (
-        'https://www.youtube.com/s/player/aa3fc80b/player_ias.vflset/en_US/base.js',
-        '0qY9dal2uzOnOGwa-48hha', 'VSh1KDfQMk-eag',
-    ),
 ]
 
 
@@ -362,8 +178,6 @@ class TestPlayerInfo(unittest.TestCase):
             ('https://www.youtube.com/s/player/64dddad9/player-plasma-ias-phone-en_US.vflset/base.js', '64dddad9'),
             ('https://www.youtube.com/s/player/64dddad9/player-plasma-ias-phone-de_DE.vflset/base.js', '64dddad9'),
             ('https://www.youtube.com/s/player/64dddad9/player-plasma-ias-tablet-en_US.vflset/base.js', '64dddad9'),
-            ('https://www.youtube.com/s/player/e7567ecf/player_ias_tce.vflset/en_US/base.js', 'e7567ecf'),
-            ('https://www.youtube.com/s/player/643afba4/tv-player-ias.vflset/tv-player-ias.js', '643afba4'),
             # obsolete
             ('https://www.youtube.com/yts/jsbin/player_ias-vfle4-e03/en_US/base.js', 'vfle4-e03'),
             ('https://www.youtube.com/yts/jsbin/player_ias-vfl49f_g4/en_US/base.js', 'vfl49f_g4'),
@@ -373,9 +187,8 @@ class TestPlayerInfo(unittest.TestCase):
             ('https://s.ytimg.com/yts/jsbin/html5player-en_US-vflXGBaUN.js', 'vflXGBaUN'),
             ('https://s.ytimg.com/yts/jsbin/html5player-en_US-vflKjOTVq/html5player.js', 'vflKjOTVq'),
         )
-        ie = YoutubeIE(FakeYDL({'cachedir': False}))
         for player_url, expected_player_id in PLAYER_URLS:
-            player_id = ie._extract_player_info(player_url)
+            player_id = YoutubeIE._extract_player_info(player_url)
             self.assertEqual(player_id, expected_player_id)
 
 
@@ -387,19 +200,21 @@ class TestSignature(unittest.TestCase):
             os.mkdir(self.TESTDATA_DIR)
 
     def tearDown(self):
-        with compat_contextlib_suppress(OSError):
+        try:
             for f in os.listdir(self.TESTDATA_DIR):
                 os.remove(f)
+        except OSError:
+            pass
 
 
 def t_factory(name, sig_func, url_pattern):
     def make_tfunc(url, sig_input, expected_sig):
         m = url_pattern.match(url)
-        assert m, '{0!r} should follow URL format'.format(url)
-        test_id = re.sub(r'[/.-]', '_', m.group('id') or m.group('compat_id'))
+        assert m, '%r should follow URL format' % url
+        test_id = m.group('id')
 
         def test_func(self):
-            basename = 'player-{0}.js'.format(test_id)
+            basename = 'player-{0}-{1}.js'.format(name, test_id)
             fn = os.path.join(self.TESTDATA_DIR, basename)
 
             if not os.path.exists(fn):
@@ -414,7 +229,7 @@ def t_factory(name, sig_func, url_pattern):
 
 
 def signature(jscode, sig_input):
-    func = YoutubeIE(FakeYDL({'cachedir': False}))._parse_sig_js(jscode)
+    func = YoutubeIE(FakeYDL())._parse_sig_js(jscode)
     src_sig = (
         compat_str(string.printable[:sig_input])
         if isinstance(sig_input, int) else sig_input)
@@ -422,23 +237,17 @@ def signature(jscode, sig_input):
 
 
 def n_sig(jscode, sig_input):
-    ie = YoutubeIE(FakeYDL({'cachedir': False}))
-    jsi = JSInterpreter(jscode)
-    jsi, _, func_code = ie._extract_n_function_code_jsi(sig_input, jsi)
-    return ie._extract_n_function_from_code(jsi, func_code)(sig_input)
+    funcname = YoutubeIE(FakeYDL())._extract_n_function_name(jscode)
+    return JSInterpreter(jscode).call_function(funcname, sig_input)
 
 
 make_sig_test = t_factory(
-    'signature', signature,
-    re.compile(r'''(?x)
-        .+/(?P<h5>html5)?player(?(h5)(?:-en_US)?-|/)(?P<id>[a-zA-Z0-9/._-]+)
-        (?(h5)/(?:watch_as3|html5player))?\.js$
-    '''))
+    'signature', signature, re.compile(r'.*-(?P<id>[a-zA-Z0-9_-]+)(?:/watch_as3|/html5player)?\.[a-z]+$'))
 for test_spec in _SIG_TESTS:
     make_sig_test(*test_spec)
 
 make_nsig_test = t_factory(
-    'nsig', n_sig, re.compile(r'.+/player/(?P<id>[a-zA-Z0-9_/.-]+)\.js$'))
+    'nsig', n_sig, re.compile(r'.+/player/(?P<id>[a-zA-Z0-9_-]+)/.+.js$'))
 for test_spec in _NSIG_TESTS:
     make_nsig_test(*test_spec)
 
diff --git a/youtube_dl/YoutubeDL.py b/youtube_dl/YoutubeDL.py
index 8367b6e53..9e5620eef 100755
--- a/youtube_dl/YoutubeDL.py
+++ b/youtube_dl/YoutubeDL.py
@@ -540,14 +540,10 @@ class YoutubeDL(object):
         """Print message to stdout if not in quiet mode."""
         return self.to_stdout(message, skip_eol, check_quiet=True)
 
-    def _write_string(self, s, out=None, only_once=False, _cache=set()):
-        if only_once and s in _cache:
-            return
+    def _write_string(self, s, out=None):
         write_string(s, out=out, encoding=self.params.get('encoding'))
-        if only_once:
-            _cache.add(s)
 
-    def to_stdout(self, message, skip_eol=False, check_quiet=False, only_once=False):
+    def to_stdout(self, message, skip_eol=False, check_quiet=False):
         """Print message to stdout if not in quiet mode."""
         if self.params.get('logger'):
             self.params['logger'].debug(message)
@@ -556,9 +552,9 @@ class YoutubeDL(object):
             terminator = ['\n', ''][skip_eol]
             output = message + terminator
 
-            self._write_string(output, self._screen_file, only_once=only_once)
+            self._write_string(output, self._screen_file)
 
-    def to_stderr(self, message, only_once=False):
+    def to_stderr(self, message):
         """Print message to stderr."""
         assert isinstance(message, compat_str)
         if self.params.get('logger'):
@@ -566,7 +562,7 @@ class YoutubeDL(object):
         else:
             message = self._bidi_workaround(message)
             output = message + '\n'
-            self._write_string(output, self._err_file, only_once=only_once)
+            self._write_string(output, self._err_file)
 
     def to_console_title(self, message):
         if not self.params.get('consoletitle', False):
@@ -645,11 +641,18 @@ class YoutubeDL(object):
             raise DownloadError(message, exc_info)
         self._download_retcode = 1
 
-    def report_warning(self, message, only_once=False):
+    def report_warning(self, message, only_once=False, _cache={}):
         '''
         Print the message to stderr, it will be prefixed with 'WARNING:'
         If stderr is a tty file the 'WARNING:' will be colored
         '''
+        if only_once:
+            m_hash = hash((self, message))
+            m_cnt = _cache.setdefault(m_hash, 0)
+            _cache[m_hash] = m_cnt + 1
+            if m_cnt > 0:
+                return
+
         if self.params.get('logger') is not None:
             self.params['logger'].warning(message)
         else:
@@ -660,7 +663,7 @@ class YoutubeDL(object):
             else:
                 _msg_header = 'WARNING:'
             warning_message = '%s %s' % (_msg_header, message)
-            self.to_stderr(warning_message, only_once=only_once)
+            self.to_stderr(warning_message)
 
     def report_error(self, message, *args, **kwargs):
         '''
@@ -674,16 +677,6 @@ class YoutubeDL(object):
         kwargs['message'] = '%s %s' % (_msg_header, message)
         self.trouble(*args, **kwargs)
 
-    def write_debug(self, message, only_once=False):
-        '''Log debug message or Print message to stderr'''
-        if not self.params.get('verbose', False):
-            return
-        message = '[debug] {0}'.format(message)
-        if self.params.get('logger'):
-            self.params['logger'].debug(message)
-        else:
-            self.to_stderr(message, only_once)
-
     def report_unscoped_cookies(self, *args, **kwargs):
         # message=None, tb=False, is_error=False
         if len(args) <= 2:
@@ -2521,7 +2514,7 @@ class YoutubeDL(object):
                 self.get_encoding()))
         write_string(encoding_str, encoding=None)
 
-        writeln_debug = lambda *s: self.write_debug(''.join(s))
+        writeln_debug = lambda *s: self._write_string('[debug] %s\n' % (''.join(s), ))
         writeln_debug('youtube-dl version ', __version__)
         if _LAZY_LOADER:
             writeln_debug('Lazy loading extractors enabled')
diff --git a/youtube_dl/__init__.py b/youtube_dl/__init__.py
index 3c1272e7b..06bdfb689 100644
--- a/youtube_dl/__init__.py
+++ b/youtube_dl/__init__.py
@@ -18,7 +18,7 @@ from .compat import (
     compat_getpass,
     compat_register_utf8,
     compat_shlex_split,
-    _workaround_optparse_bug9161,
+    workaround_optparse_bug9161,
 )
 from .utils import (
     _UnsafeExtensionError,
@@ -50,7 +50,7 @@ def _real_main(argv=None):
     # Compatibility fix for Windows
     compat_register_utf8()
 
-    _workaround_optparse_bug9161()
+    workaround_optparse_bug9161()
 
     setproctitle('youtube-dl')
 
diff --git a/youtube_dl/cache.py b/youtube_dl/cache.py
index eb0a729c2..54123da0e 100644
--- a/youtube_dl/cache.py
+++ b/youtube_dl/cache.py
@@ -1,4 +1,3 @@
-# coding: utf-8
 from __future__ import unicode_literals
 
 import errno
@@ -11,14 +10,12 @@ import traceback
 from .compat import (
     compat_getenv,
     compat_open as open,
-    compat_os_makedirs,
 )
 from .utils import (
     error_to_compat_str,
-    escape_rfc3986,
     expand_path,
     is_outdated_version,
-    traverse_obj,
+    try_get,
     write_json_file,
 )
 from .version import __version__
@@ -33,35 +30,23 @@ class Cache(object):
     def __init__(self, ydl):
         self._ydl = ydl
 
-    def _write_debug(self, *args, **kwargs):
-        self._ydl.write_debug(*args, **kwargs)
-
-    def _report_warning(self, *args, **kwargs):
-        self._ydl.report_warning(*args, **kwargs)
-
-    def _to_screen(self, *args, **kwargs):
-        self._ydl.to_screen(*args, **kwargs)
-
-    def _get_param(self, k, default=None):
-        return self._ydl.params.get(k, default)
-
     def _get_root_dir(self):
-        res = self._get_param('cachedir')
+        res = self._ydl.params.get('cachedir')
         if res is None:
             cache_root = compat_getenv('XDG_CACHE_HOME', '~/.cache')
             res = os.path.join(cache_root, self._YTDL_DIR)
         return expand_path(res)
 
     def _get_cache_fn(self, section, key, dtype):
-        assert re.match(r'^[\w.-]+$', section), \
+        assert re.match(r'^[a-zA-Z0-9_.-]+$', section), \
             'invalid section %r' % section
-        key = escape_rfc3986(key, safe='').replace('%', ',')  # encode non-ascii characters
+        assert re.match(r'^[a-zA-Z0-9_.-]+$', key), 'invalid key %r' % key
         return os.path.join(
             self._get_root_dir(), section, '%s.%s' % (key, dtype))
 
     @property
     def enabled(self):
-        return self._get_param('cachedir') is not False
+        return self._ydl.params.get('cachedir') is not False
 
     def store(self, section, key, data, dtype='json'):
         assert dtype in ('json',)
@@ -71,75 +56,61 @@ class Cache(object):
 
         fn = self._get_cache_fn(section, key, dtype)
         try:
-            compat_os_makedirs(os.path.dirname(fn), exist_ok=True)
-            self._write_debug('Saving {section}.{key} to cache'.format(section=section, key=key))
+            try:
+                os.makedirs(os.path.dirname(fn))
+            except OSError as ose:
+                if ose.errno != errno.EEXIST:
+                    raise
             write_json_file({self._VERSION_KEY: __version__, 'data': data}, fn)
         except Exception:
             tb = traceback.format_exc()
-            self._report_warning('Writing cache to {fn!r} failed: {tb}'.format(fn=fn, tb=tb))
-
-    def clear(self, section, key, dtype='json'):
-
-        if not self.enabled:
-            return
-
-        fn = self._get_cache_fn(section, key, dtype)
-        self._write_debug('Clearing {section}.{key} from cache'.format(section=section, key=key))
-        try:
-            os.remove(fn)
-        except Exception as e:
-            if getattr(e, 'errno') == errno.ENOENT:
-                # file not found
-                return
-            tb = traceback.format_exc()
-            self._report_warning('Clearing cache from {fn!r} failed: {tb}'.format(fn=fn, tb=tb))
+            self._ydl.report_warning(
+                'Writing cache to %r failed: %s' % (fn, tb))
 
     def _validate(self, data, min_ver):
-        version = traverse_obj(data, self._VERSION_KEY)
+        version = try_get(data, lambda x: x[self._VERSION_KEY])
         if not version:  # Backward compatibility
             data, version = {'data': data}, self._DEFAULT_VERSION
         if not is_outdated_version(version, min_ver or '0', assume_new=False):
             return data['data']
-        self._write_debug('Discarding old cache from version {version} (needs {min_ver})'.format(version=version, min_ver=min_ver))
+        self._ydl.to_screen(
+            'Discarding old cache from version {version} (needs {min_ver})'.format(**locals()))
 
-    def load(self, section, key, dtype='json', default=None, **kw_min_ver):
+    def load(self, section, key, dtype='json', default=None, min_ver=None):
         assert dtype in ('json',)
-        min_ver = kw_min_ver.get('min_ver')
 
         if not self.enabled:
             return default
 
         cache_fn = self._get_cache_fn(section, key, dtype)
         try:
-            with open(cache_fn, encoding='utf-8') as cachef:
-                self._write_debug('Loading {section}.{key} from cache'.format(section=section, key=key), only_once=True)
-                return self._validate(json.load(cachef), min_ver)
-        except (ValueError, KeyError):
             try:
-                file_size = 'size: %d' % os.path.getsize(cache_fn)
-            except (OSError, IOError) as oe:
-                file_size = error_to_compat_str(oe)
-            self._report_warning('Cache retrieval from %s failed (%s)' % (cache_fn, file_size))
-        except Exception as e:
-            if getattr(e, 'errno') == errno.ENOENT:
-                # no cache available
-                return
-            self._report_warning('Cache retrieval from %s failed' % (cache_fn,))
+                with open(cache_fn, 'r', encoding='utf-8') as cachef:
+                    return self._validate(json.load(cachef), min_ver)
+            except ValueError:
+                try:
+                    file_size = os.path.getsize(cache_fn)
+                except (OSError, IOError) as oe:
+                    file_size = error_to_compat_str(oe)
+                self._ydl.report_warning(
+                    'Cache retrieval from %s failed (%s)' % (cache_fn, file_size))
+        except IOError:
+            pass  # No cache available
 
         return default
 
     def remove(self):
         if not self.enabled:
-            self._to_screen('Cache is disabled (Did you combine --no-cache-dir and --rm-cache-dir?)')
+            self._ydl.to_screen('Cache is disabled (Did you combine --no-cache-dir and --rm-cache-dir?)')
             return
 
         cachedir = self._get_root_dir()
         if not any((term in cachedir) for term in ('cache', 'tmp')):
-            raise Exception('Not removing directory %s - this does not look like a cache dir' % (cachedir,))
+            raise Exception('Not removing directory %s - this does not look like a cache dir' % cachedir)
 
-        self._to_screen(
-            'Removing cache dir %s .' % (cachedir,), skip_eol=True, ),
+        self._ydl.to_screen(
+            'Removing cache dir %s .' % cachedir, skip_eol=True)
         if os.path.exists(cachedir):
-            self._to_screen('.', skip_eol=True)
+            self._ydl.to_screen('.', skip_eol=True)
             shutil.rmtree(cachedir)
-        self._to_screen('.')
+        self._ydl.to_screen('.')
diff --git a/youtube_dl/casefold.py b/youtube_dl/casefold.py
index 712b2e7fa..ad9c66f8e 100644
--- a/youtube_dl/casefold.py
+++ b/youtube_dl/casefold.py
@@ -10,10 +10,9 @@ from .compat import (
 # https://github.com/unicode-org/icu/blob/main/icu4c/source/data/unidata/CaseFolding.txt
 # In case newly foldable Unicode characters are defined, paste the new version
 # of the text inside the ''' marks.
-# The text is expected to have only blank lines and lines with 1st character #,
+# The text is expected to have only blank lines andlines with 1st character #,
 # all ignored, and fold definitions like this:
-# `from_hex_code; status; space_separated_to_hex_code_list; comment`
-# Only `status` C/F are used.
+# `from_hex_code; space_separated_to_hex_code_list; comment`
 
 _map_str = '''
 # CaseFolding-15.0.0.txt
@@ -1658,6 +1657,11 @@ _map = dict(
 del _map_str
 
 
-def _casefold(s):
+def casefold(s):
     assert isinstance(s, compat_str)
     return ''.join((_map.get(c, c) for c in s))
+
+
+__all__ = [
+    'casefold',
+]
diff --git a/youtube_dl/compat.py b/youtube_dl/compat.py
index ebe22bdf9..ed1a33cf2 100644
--- a/youtube_dl/compat.py
+++ b/youtube_dl/compat.py
@@ -16,6 +16,7 @@ import os
 import platform
 import re
 import shlex
+import shutil
 import socket
 import struct
 import subprocess
@@ -23,15 +24,11 @@ import sys
 import types
 import xml.etree.ElementTree
 
-_IDENTITY = lambda x: x
-
 # naming convention
 # 'compat_' + Python3_name.replace('.', '_')
 # other aliases exist for convenience and/or legacy
-# wrap disposable test values in type() to reclaim storage
 
-# deal with critical unicode/str things first:
-# compat_str, compat_basestring, compat_chr
+# deal with critical unicode/str things first
 try:
     # Python 2
     compat_str, compat_basestring, compat_chr = (
@@ -42,23 +39,18 @@ except NameError:
         str, (str, bytes), chr
     )
 
-
-# compat_casefold
+# casefold
 try:
     compat_str.casefold
     compat_casefold = lambda s: s.casefold()
 except AttributeError:
-    from .casefold import _casefold as compat_casefold
+    from .casefold import casefold as compat_casefold
 
-
-# compat_collections_abc
 try:
     import collections.abc as compat_collections_abc
 except ImportError:
     import collections as compat_collections_abc
 
-
-# compat_urllib_request
 try:
     import urllib.request as compat_urllib_request
 except ImportError:  # Python 2
@@ -87,15 +79,11 @@ except TypeError:
     _add_init_method_arg(compat_urllib_request.Request)
     del _add_init_method_arg
 
-
-# compat_urllib_error
 try:
     import urllib.error as compat_urllib_error
 except ImportError:  # Python 2
     import urllib2 as compat_urllib_error
 
-
-# compat_urllib_parse
 try:
     import urllib.parse as compat_urllib_parse
 except ImportError:  # Python 2
@@ -110,23 +98,17 @@ except ImportError:  # Python 2
 compat_urlparse = compat_urllib_parse
 compat_urllib_parse_urlparse = compat_urllib_parse.urlparse
 
-
-# compat_urllib_response
 try:
     import urllib.response as compat_urllib_response
 except ImportError:  # Python 2
     import urllib as compat_urllib_response
 
-
-# compat_urllib_response.addinfourl
 try:
     compat_urllib_response.addinfourl.status
 except AttributeError:
     # .getcode() is deprecated in Py 3.
     compat_urllib_response.addinfourl.status = property(lambda self: self.getcode())
 
-
-# compat_http_cookiejar
 try:
     import http.cookiejar as compat_cookiejar
 except ImportError:  # Python 2
@@ -145,16 +127,12 @@ else:
     compat_cookiejar_Cookie = compat_cookiejar.Cookie
 compat_http_cookiejar_Cookie = compat_cookiejar_Cookie
 
-
-# compat_http_cookies
 try:
     import http.cookies as compat_cookies
 except ImportError:  # Python 2
     import Cookie as compat_cookies
 compat_http_cookies = compat_cookies
 
-
-# compat_http_cookies_SimpleCookie
 if sys.version_info[0] == 2 or sys.version_info < (3, 3):
     class compat_cookies_SimpleCookie(compat_cookies.SimpleCookie):
         def load(self, rawdata):
@@ -177,15 +155,11 @@ else:
     compat_cookies_SimpleCookie = compat_cookies.SimpleCookie
 compat_http_cookies_SimpleCookie = compat_cookies_SimpleCookie
 
-
-# compat_html_entities, probably useless now
 try:
     import html.entities as compat_html_entities
 except ImportError:  # Python 2
     import htmlentitydefs as compat_html_entities
 
-
-# compat_html_entities_html5
 try:  # Python >= 3.3
     compat_html_entities_html5 = compat_html_entities.html5
 except AttributeError:
@@ -2434,24 +2408,18 @@ except AttributeError:
     # Py < 3.1
     compat_http_client.HTTPResponse.getcode = lambda self: self.status
 
-
-# compat_urllib_HTTPError
 try:
     from urllib.error import HTTPError as compat_HTTPError
 except ImportError:  # Python 2
     from urllib2 import HTTPError as compat_HTTPError
 compat_urllib_HTTPError = compat_HTTPError
 
-
-# compat_urllib_request_urlretrieve
 try:
     from urllib.request import urlretrieve as compat_urlretrieve
 except ImportError:  # Python 2
     from urllib import urlretrieve as compat_urlretrieve
 compat_urllib_request_urlretrieve = compat_urlretrieve
 
-
-# compat_html_parser_HTMLParser, compat_html_parser_HTMLParseError
 try:
     from HTMLParser import (
         HTMLParser as compat_HTMLParser,
@@ -2464,33 +2432,22 @@ except ImportError:  # Python 3
         # HTMLParseError was deprecated in Python 3.3 and removed in
         # Python 3.5. Introducing dummy exception for Python >3.5 for compatible
         # and uniform cross-version exception handling
-
         class compat_HTMLParseError(Exception):
             pass
-
 compat_html_parser_HTMLParser = compat_HTMLParser
 compat_html_parser_HTMLParseError = compat_HTMLParseError
 
-
-# compat_subprocess_get_DEVNULL
 try:
     _DEVNULL = subprocess.DEVNULL
     compat_subprocess_get_DEVNULL = lambda: _DEVNULL
 except AttributeError:
     compat_subprocess_get_DEVNULL = lambda: open(os.path.devnull, 'w')
 
-
-# compat_http_server
 try:
     import http.server as compat_http_server
 except ImportError:
     import BaseHTTPServer as compat_http_server
 
-
-# compat_urllib_parse_unquote_to_bytes,
-# compat_urllib_parse_unquote, compat_urllib_parse_unquote_plus,
-# compat_urllib_parse_urlencode,
-# compat_urllib_parse_parse_qs
 try:
     from urllib.parse import unquote_to_bytes as compat_urllib_parse_unquote_to_bytes
     from urllib.parse import unquote as compat_urllib_parse_unquote
@@ -2498,7 +2455,8 @@ try:
     from urllib.parse import urlencode as compat_urllib_parse_urlencode
     from urllib.parse import parse_qs as compat_parse_qs
 except ImportError:  # Python 2
-    _asciire = getattr(compat_urllib_parse, '_asciire', None) or re.compile(r'([\x00-\x7f]+)')
+    _asciire = (compat_urllib_parse._asciire if hasattr(compat_urllib_parse, '_asciire')
+                else re.compile(r'([\x00-\x7f]+)'))
 
     # HACK: The following are the correct unquote_to_bytes, unquote and unquote_plus
     # implementations from cpython 3.4.3's stdlib. Python 2's version
@@ -2566,21 +2524,24 @@ except ImportError:  # Python 2
     # Possible solutions are to either port it from python 3 with all
     # the friends or manually ensure input query contains only byte strings.
     # We will stick with latter thus recursively encoding the whole query.
-    def compat_urllib_parse_urlencode(query, doseq=0, safe='', encoding='utf-8', errors='strict'):
-
+    def compat_urllib_parse_urlencode(query, doseq=0, encoding='utf-8'):
         def encode_elem(e):
             if isinstance(e, dict):
                 e = encode_dict(e)
             elif isinstance(e, (list, tuple,)):
-                e = type(e)(encode_elem(el) for el in e)
+                list_e = encode_list(e)
+                e = tuple(list_e) if isinstance(e, tuple) else list_e
             elif isinstance(e, compat_str):
-                e = e.encode(encoding, errors)
+                e = e.encode(encoding)
             return e
 
         def encode_dict(d):
-            return tuple((encode_elem(k), encode_elem(v)) for k, v in d.items())
+            return dict((encode_elem(k), encode_elem(v)) for k, v in d.items())
 
-        return compat_urllib_parse._urlencode(encode_elem(query), doseq=doseq).decode('ascii')
+        def encode_list(l):
+            return [encode_elem(e) for e in l]
+
+        return compat_urllib_parse._urlencode(encode_elem(query), doseq=doseq)
 
     # HACK: The following is the correct parse_qs implementation from cpython 3's stdlib.
     # Python 2's version is apparently totally broken
@@ -2635,61 +2596,8 @@ except ImportError:  # Python 2
             ('parse_qs', compat_parse_qs)):
         setattr(compat_urllib_parse, name, fix)
 
-    try:
-        all(chr(i) in b'' for i in range(256))
-    except TypeError:
-        # not all chr(i) are str: patch Python2 quote
-
-        _safemaps = getattr(compat_urllib_parse, '_safemaps', {})
-        _always_safe = frozenset(compat_urllib_parse.always_safe)
-
-        def _quote(s, safe='/'):
-            """quote('abc def') -> 'abc%20def'"""
-
-            if not s and s is not None:  # fast path
-                return s
-            safe = frozenset(safe)
-            cachekey = (safe, _always_safe)
-            try:
-                safe_map = _safemaps[cachekey]
-            except KeyError:
-                safe = _always_safe | safe
-                safe_map = {}
-                for i in range(256):
-                    c = chr(i)
-                    safe_map[c] = (
-                        c if (i < 128 and c in safe)
-                        else b'%{0:02X}'.format(i))
-                _safemaps[cachekey] = safe_map
-
-            if safe.issuperset(s):
-                return s
-            return ''.join(safe_map[c] for c in s)
-
-        # linked code
-        def _quote_plus(s, safe=''):
-            return (
-                _quote(s, safe + b' ').replace(b' ', b'+') if b' ' in s
-                else _quote(s, safe))
-
-        # linked code
-        def _urlcleanup():
-            if compat_urllib_parse._urlopener:
-                compat_urllib_parse._urlopener.cleanup()
-            _safemaps.clear()
-            compat_urllib_parse.ftpcache.clear()
-
-        for name, fix in (
-                ('quote', _quote),
-                ('quote_plus', _quote_plus),
-                ('urlcleanup', _urlcleanup)):
-            setattr(compat_urllib_parse, '_' + name, getattr(compat_urllib_parse, name))
-            setattr(compat_urllib_parse, name, fix)
-
 compat_urllib_parse_parse_qs = compat_parse_qs
 
-
-# compat_urllib_request_DataHandler
 try:
     from urllib.request import DataHandler as compat_urllib_request_DataHandler
 except ImportError:  # Python < 3.4
@@ -2724,20 +2632,16 @@ except ImportError:  # Python < 3.4
 
             return compat_urllib_response.addinfourl(io.BytesIO(data), headers, url)
 
-
-# compat_xml_etree_ElementTree_ParseError
 try:
     from xml.etree.ElementTree import ParseError as compat_xml_parse_error
 except ImportError:  # Python 2.6
     from xml.parsers.expat import ExpatError as compat_xml_parse_error
 compat_xml_etree_ElementTree_ParseError = compat_xml_parse_error
 
-
-# compat_xml_etree_ElementTree_Element
-_etree = xml.etree.ElementTree
+etree = xml.etree.ElementTree
 
 
-class _TreeBuilder(_etree.TreeBuilder):
+class _TreeBuilder(etree.TreeBuilder):
     def doctype(self, name, pubid, system):
         pass
 
@@ -2746,7 +2650,7 @@ try:
     # xml.etree.ElementTree.Element is a method in Python <=2.6 and
     # the following will crash with:
     #  TypeError: isinstance() arg 2 must be a class, type, or tuple of classes and types
-    isinstance(None, _etree.Element)
+    isinstance(None, etree.Element)
     from xml.etree.ElementTree import Element as compat_etree_Element
 except TypeError:  # Python <=2.6
     from xml.etree.ElementTree import _ElementInterface as compat_etree_Element
@@ -2754,12 +2658,12 @@ compat_xml_etree_ElementTree_Element = compat_etree_Element
 
 if sys.version_info[0] >= 3:
     def compat_etree_fromstring(text):
-        return _etree.XML(text, parser=_etree.XMLParser(target=_TreeBuilder()))
+        return etree.XML(text, parser=etree.XMLParser(target=_TreeBuilder()))
 else:
     # python 2.x tries to encode unicode strings with ascii (see the
     # XMLParser._fixtext method)
     try:
-        _etree_iter = _etree.Element.iter
+        _etree_iter = etree.Element.iter
     except AttributeError:  # Python <=2.6
         def _etree_iter(root):
             for el in root.findall('*'):
@@ -2771,29 +2675,27 @@ else:
     # 2.7 source
     def _XML(text, parser=None):
         if not parser:
-            parser = _etree.XMLParser(target=_TreeBuilder())
+            parser = etree.XMLParser(target=_TreeBuilder())
         parser.feed(text)
         return parser.close()
 
     def _element_factory(*args, **kwargs):
-        el = _etree.Element(*args, **kwargs)
+        el = etree.Element(*args, **kwargs)
         for k, v in el.items():
             if isinstance(v, bytes):
                 el.set(k, v.decode('utf-8'))
         return el
 
     def compat_etree_fromstring(text):
-        doc = _XML(text, parser=_etree.XMLParser(target=_TreeBuilder(element_factory=_element_factory)))
+        doc = _XML(text, parser=etree.XMLParser(target=_TreeBuilder(element_factory=_element_factory)))
         for el in _etree_iter(doc):
             if el.text is not None and isinstance(el.text, bytes):
                 el.text = el.text.decode('utf-8')
         return doc
 
-
-# compat_xml_etree_register_namespace
-try:
-    compat_etree_register_namespace = _etree.register_namespace
-except AttributeError:
+if hasattr(etree, 'register_namespace'):
+    compat_etree_register_namespace = etree.register_namespace
+else:
     def compat_etree_register_namespace(prefix, uri):
         """Register a namespace prefix.
         The registry is global, and any existing mapping for either the
@@ -2802,16 +2704,14 @@ except AttributeError:
         attributes in this namespace will be serialized with prefix if possible.
         ValueError is raised if prefix is reserved or is invalid.
         """
-        if re.match(r'ns\d+$', prefix):
-            raise ValueError('Prefix format reserved for internal use')
-        for k, v in list(_etree._namespace_map.items()):
+        if re.match(r"ns\d+$", prefix):
+            raise ValueError("Prefix format reserved for internal use")
+        for k, v in list(etree._namespace_map.items()):
             if k == uri or v == prefix:
-                del _etree._namespace_map[k]
-        _etree._namespace_map[uri] = prefix
+                del etree._namespace_map[k]
+        etree._namespace_map[uri] = prefix
 compat_xml_etree_register_namespace = compat_etree_register_namespace
 
-
-# compat_xpath, compat_etree_iterfind
 if sys.version_info < (2, 7):
     # Here comes the crazy part: In 2.6, if the xpath is a unicode,
     # .//node does not match if a node is a direct child of . !
@@ -2998,6 +2898,7 @@ if sys.version_info < (2, 7):
         def __init__(self, root):
             self.root = root
 
+    ##
     # Generate all matching objects.
 
     def compat_etree_iterfind(elem, path, namespaces=None):
@@ -3032,15 +2933,13 @@ if sys.version_info < (2, 7):
 
 
 else:
+    compat_xpath = lambda xpath: xpath
     compat_etree_iterfind = lambda element, match: element.iterfind(match)
-    compat_xpath = _IDENTITY
 
 
-# compat_os_name
 compat_os_name = os._name if os.name == 'java' else os.name
 
 
-# compat_shlex_quote
 if compat_os_name == 'nt':
     def compat_shlex_quote(s):
         return s if re.match(r'^[-_\w./]+$', s) else '"%s"' % s.replace('"', '\\"')
@@ -3055,7 +2954,6 @@ else:
                 return "'" + s.replace("'", "'\"'\"'") + "'"
 
 
-# compat_shlex.split
 try:
     args = shlex.split('中文')
     assert (isinstance(args, list)
@@ -3071,7 +2969,6 @@ except (AssertionError, UnicodeEncodeError):
         return list(map(lambda s: s.decode('utf-8'), shlex.split(s, comments, posix)))
 
 
-# compat_ord
 def compat_ord(c):
     if isinstance(c, int):
         return c
@@ -3079,7 +2976,6 @@ def compat_ord(c):
         return ord(c)
 
 
-# compat_getenv, compat_os_path_expanduser, compat_setenv
 if sys.version_info >= (3, 0):
     compat_getenv = os.getenv
     compat_expanduser = os.path.expanduser
@@ -3167,22 +3063,6 @@ else:
 compat_os_path_expanduser = compat_expanduser
 
 
-# compat_os_makedirs
-try:
-    os.makedirs('.', exist_ok=True)
-    compat_os_makedirs = os.makedirs
-except TypeError:  # < Py3.2
-    from errno import EEXIST as _errno_EEXIST
-
-    def compat_os_makedirs(name, mode=0o777, exist_ok=False):
-        try:
-            return os.makedirs(name, mode=mode)
-        except OSError as ose:
-            if not (exist_ok and ose.errno == _errno_EEXIST):
-                raise
-
-
-# compat_os_path_realpath
 if compat_os_name == 'nt' and sys.version_info < (3, 8):
     # os.path.realpath on Windows does not follow symbolic links
     # prior to Python 3.8 (see https://bugs.python.org/issue9949)
@@ -3196,7 +3076,6 @@ else:
 compat_os_path_realpath = compat_realpath
 
 
-# compat_print
 if sys.version_info < (3, 0):
     def compat_print(s):
         from .utils import preferredencoding
@@ -3207,7 +3086,6 @@ else:
         print(s)
 
 
-# compat_getpass_getpass
 if sys.version_info < (3, 0) and sys.platform == 'win32':
     def compat_getpass(prompt, *args, **kwargs):
         if isinstance(prompt, compat_str):
@@ -3220,42 +3098,36 @@ else:
 compat_getpass_getpass = compat_getpass
 
 
-# compat_input
 try:
     compat_input = raw_input
 except NameError:  # Python 3
     compat_input = input
 
 
-# compat_kwargs
 # Python < 2.6.5 require kwargs to be bytes
 try:
-    (lambda x: x)(**{'x': 0})
+    def _testfunc(x):
+        pass
+    _testfunc(**{'x': 0})
 except TypeError:
     def compat_kwargs(kwargs):
         return dict((bytes(k), v) for k, v in kwargs.items())
 else:
-    compat_kwargs = _IDENTITY
+    compat_kwargs = lambda kwargs: kwargs
 
 
-# compat_numeric_types
 try:
     compat_numeric_types = (int, float, long, complex)
 except NameError:  # Python 3
     compat_numeric_types = (int, float, complex)
 
 
-# compat_integer_types
 try:
     compat_integer_types = (int, long)
 except NameError:  # Python 3
     compat_integer_types = (int, )
 
-# compat_int
-compat_int = compat_integer_types[-1]
 
-
-# compat_socket_create_connection
 if sys.version_info < (2, 7):
     def compat_socket_create_connection(address, timeout, source_address=None):
         host, port = address
@@ -3282,7 +3154,6 @@ else:
     compat_socket_create_connection = socket.create_connection
 
 
-# compat_contextlib_suppress
 try:
     from contextlib import suppress as compat_contextlib_suppress
 except ImportError:
@@ -3325,12 +3196,12 @@ except AttributeError:
                         # repeated .close() is OK, but just in case
                         with compat_contextlib_suppress(EnvironmentError):
                             f.close()
-            popen.wait()
+                popen.wait()
 
 
 # Fix https://github.com/ytdl-org/youtube-dl/issues/4223
 # See http://bugs.python.org/issue9161 for what is broken
-def _workaround_optparse_bug9161():
+def workaround_optparse_bug9161():
     op = optparse.OptionParser()
     og = optparse.OptionGroup(op, 'foo')
     try:
@@ -3349,10 +3220,9 @@ def _workaround_optparse_bug9161():
         optparse.OptionGroup.add_option = _compat_add_option
 
 
-# compat_shutil_get_terminal_size
-try:
-    from shutil import get_terminal_size as compat_get_terminal_size  # Python >= 3.3
-except ImportError:
+if hasattr(shutil, 'get_terminal_size'):  # Python >= 3.3
+    compat_get_terminal_size = shutil.get_terminal_size
+else:
     _terminal_size = collections.namedtuple('terminal_size', ['columns', 'lines'])
 
     def compat_get_terminal_size(fallback=(80, 24)):
@@ -3382,33 +3252,27 @@ except ImportError:
                 columns = _columns
             if lines is None or lines <= 0:
                 lines = _lines
-
         return _terminal_size(columns, lines)
 
-compat_shutil_get_terminal_size = compat_get_terminal_size
 
-
-# compat_itertools_count
 try:
-    type(itertools.count(start=0, step=1))
+    itertools.count(start=0, step=1)
     compat_itertools_count = itertools.count
-except TypeError:  # Python 2.6 lacks step
+except TypeError:  # Python 2.6
     def compat_itertools_count(start=0, step=1):
         while True:
             yield start
             start += step
 
 
-# compat_tokenize_tokenize
 if sys.version_info >= (3, 0):
     from tokenize import tokenize as compat_tokenize_tokenize
 else:
     from tokenize import generate_tokens as compat_tokenize_tokenize
 
 
-# compat_struct_pack, compat_struct_unpack, compat_Struct
 try:
-    type(struct.pack('!I', 0))
+    struct.pack('!I', 0)
 except TypeError:
     # In Python 2.6 and 2.7.x < 2.7.7, struct requires a bytes argument
     # See https://bugs.python.org/issue19099
@@ -3440,10 +3304,8 @@ else:
         compat_Struct = struct.Struct
 
 
-# builtins returning an iterator
-
-# compat_map, compat_filter
-# supposedly the same versioning as for zip below
+# compat_map/filter() returning an iterator, supposedly the
+# same versioning as for zip below
 try:
     from future_builtins import map as compat_map
 except ImportError:
@@ -3460,7 +3322,6 @@ except ImportError:
     except ImportError:
         compat_filter = filter
 
-# compat_zip
 try:
     from future_builtins import zip as compat_zip
 except ImportError:  # not 2.6+ or is 3.x
@@ -3470,7 +3331,6 @@ except ImportError:  # not 2.6+ or is 3.x
         compat_zip = zip
 
 
-# compat_itertools_zip_longest
 # method renamed between Py2/3
 try:
     from itertools import zip_longest as compat_itertools_zip_longest
@@ -3478,8 +3338,7 @@ except ImportError:
     from itertools import izip_longest as compat_itertools_zip_longest
 
 
-# compat_collections_chain_map
-# collections.ChainMap: new class
+# new class in collections
 try:
     from collections import ChainMap as compat_collections_chain_map
     # Py3.3's ChainMap is deficient
@@ -3535,22 +3394,19 @@ except ImportError:
         def new_child(self, m=None, **kwargs):
             m = m or {}
             m.update(kwargs)
-            # support inheritance !
-            return type(self)(m, *self.maps)
+            return compat_collections_chain_map(m, *self.maps)
 
         @property
         def parents(self):
-            return type(self)(*(self.maps[1:]))
+            return compat_collections_chain_map(*(self.maps[1:]))
 
 
-# compat_re_Pattern, compat_re_Match
 # Pythons disagree on the type of a pattern (RegexObject, _sre.SRE_Pattern, Pattern, ...?)
 compat_re_Pattern = type(re.compile(''))
 # and on the type of a match
 compat_re_Match = type(re.match('a', 'a'))
 
 
-# compat_base64_b64decode
 if sys.version_info < (3, 3):
     def compat_b64decode(s, *args, **kwargs):
         if isinstance(s, compat_str):
@@ -3562,7 +3418,6 @@ else:
 compat_base64_b64decode = compat_b64decode
 
 
-# compat_ctypes_WINFUNCTYPE
 if platform.python_implementation() == 'PyPy' and sys.pypy_version_info < (5, 4, 0):
     # PyPy2 prior to version 5.4.0 expects byte strings as Windows function
     # names, see the original PyPy issue [1] and the youtube-dl one [2].
@@ -3581,7 +3436,6 @@ else:
         return ctypes.WINFUNCTYPE(*args, **kwargs)
 
 
-# compat_open
 if sys.version_info < (3, 0):
     # open(file, mode='r', buffering=- 1, encoding=None, errors=None, newline=None, closefd=True) not: opener=None
     def compat_open(file_, *args, **kwargs):
@@ -3609,28 +3463,18 @@ except AttributeError:
     def compat_datetime_timedelta_total_seconds(td):
         return (td.microseconds + (td.seconds + td.days * 24 * 3600) * 10**6) / 10**6
 
-
 # optional decompression packages
-# compat_brotli
 # PyPi brotli package implements 'br' Content-Encoding
 try:
     import brotli as compat_brotli
 except ImportError:
     compat_brotli = None
-# compat_ncompress
 # PyPi ncompress package implements 'compress' Content-Encoding
 try:
     import ncompress as compat_ncompress
 except ImportError:
     compat_ncompress = None
 
-# compat_zstandard
-# PyPi zstandard package implements 'zstd' Content-Encoding (RFC 8878 7.2)
-try:
-    import zstandard as compat_zstandard
-except ImportError:
-    compat_zstandard = None
-
 
 legacy = [
     'compat_HTMLParseError',
@@ -3647,7 +3491,6 @@ legacy = [
     'compat_getpass',
     'compat_parse_qs',
     'compat_realpath',
-    'compat_shlex_split',
     'compat_urllib_parse_parse_qs',
     'compat_urllib_parse_unquote',
     'compat_urllib_parse_unquote_plus',
@@ -3661,6 +3504,8 @@ legacy = [
 
 
 __all__ = [
+    'compat_html_parser_HTMLParseError',
+    'compat_html_parser_HTMLParser',
     'compat_Struct',
     'compat_base64_b64decode',
     'compat_basestring',
@@ -3669,9 +3514,13 @@ __all__ = [
     'compat_chr',
     'compat_collections_abc',
     'compat_collections_chain_map',
+    'compat_datetime_timedelta_total_seconds',
+    'compat_http_cookiejar',
+    'compat_http_cookiejar_Cookie',
+    'compat_http_cookies',
+    'compat_http_cookies_SimpleCookie',
     'compat_contextlib_suppress',
     'compat_ctypes_WINFUNCTYPE',
-    'compat_datetime_timedelta_total_seconds',
     'compat_etree_fromstring',
     'compat_etree_iterfind',
     'compat_filter',
@@ -3680,16 +3529,9 @@ __all__ = [
     'compat_getpass_getpass',
     'compat_html_entities',
     'compat_html_entities_html5',
-    'compat_html_parser_HTMLParseError',
-    'compat_html_parser_HTMLParser',
-    'compat_http_cookiejar',
-    'compat_http_cookiejar_Cookie',
-    'compat_http_cookies',
-    'compat_http_cookies_SimpleCookie',
     'compat_http_client',
     'compat_http_server',
     'compat_input',
-    'compat_int',
     'compat_integer_types',
     'compat_itertools_count',
     'compat_itertools_zip_longest',
@@ -3699,7 +3541,6 @@ __all__ = [
     'compat_numeric_types',
     'compat_open',
     'compat_ord',
-    'compat_os_makedirs',
     'compat_os_name',
     'compat_os_path_expanduser',
     'compat_os_path_realpath',
@@ -3709,7 +3550,7 @@ __all__ = [
     'compat_register_utf8',
     'compat_setenv',
     'compat_shlex_quote',
-    'compat_shutil_get_terminal_size',
+    'compat_shlex_split',
     'compat_socket_create_connection',
     'compat_str',
     'compat_struct_pack',
@@ -3729,5 +3570,5 @@ __all__ = [
     'compat_xml_etree_register_namespace',
     'compat_xpath',
     'compat_zip',
-    'compat_zstandard',
+    'workaround_optparse_bug9161',
 ]
diff --git a/youtube_dl/extractor/bokecc.py b/youtube_dl/extractor/bokecc.py
index 4b8bef391..6017e8344 100644
--- a/youtube_dl/extractor/bokecc.py
+++ b/youtube_dl/extractor/bokecc.py
@@ -32,7 +32,7 @@ class BokeCCBaseIE(InfoExtractor):
 
 
 class BokeCCIE(BokeCCBaseIE):
-    IE_DESC = 'CC视频'
+    _IE_DESC = 'CC视频'
     _VALID_URL = r'https?://union\.bokecc\.com/playvideo\.bo\?(?P<query>.*)'
 
     _TESTS = [{
diff --git a/youtube_dl/extractor/cloudy.py b/youtube_dl/extractor/cloudy.py
index d39a9a5c2..85ca20ecc 100644
--- a/youtube_dl/extractor/cloudy.py
+++ b/youtube_dl/extractor/cloudy.py
@@ -9,7 +9,7 @@ from ..utils import (
 
 
 class CloudyIE(InfoExtractor):
-    IE_DESC = 'cloudy.ec'
+    _IE_DESC = 'cloudy.ec'
     _VALID_URL = r'https?://(?:www\.)?cloudy\.ec/(?:v/|embed\.php\?.*?\bid=)(?P<id>[A-Za-z0-9]+)'
     _TESTS = [{
         'url': 'https://www.cloudy.ec/v/af511e2527aac',
diff --git a/youtube_dl/extractor/common.py b/youtube_dl/extractor/common.py
index a64fcfccc..9b0016d07 100644
--- a/youtube_dl/extractor/common.py
+++ b/youtube_dl/extractor/common.py
@@ -422,8 +422,6 @@ class InfoExtractor(object):
     _GEO_COUNTRIES = None
     _GEO_IP_BLOCKS = None
     _WORKING = True
-    # supply this in public subclasses: used in supported sites list, etc
-    # IE_DESC = 'short description of IE'
 
     def __init__(self, downloader=None):
         """Constructor. Receives an optional downloader."""
@@ -505,7 +503,7 @@ class InfoExtractor(object):
         if not self._x_forwarded_for_ip:
 
             # Geo bypass mechanism is explicitly disabled by user
-            if not self.get_param('geo_bypass', True):
+            if not self._downloader.params.get('geo_bypass', True):
                 return
 
             if not geo_bypass_context:
@@ -527,7 +525,7 @@ class InfoExtractor(object):
 
             # Explicit IP block specified by user, use it right away
             # regardless of whether extractor is geo bypassable or not
-            ip_block = self.get_param('geo_bypass_ip_block', None)
+            ip_block = self._downloader.params.get('geo_bypass_ip_block', None)
 
             # Otherwise use random IP block from geo bypass context but only
             # if extractor is known as geo bypassable
@@ -538,8 +536,8 @@ class InfoExtractor(object):
 
             if ip_block:
                 self._x_forwarded_for_ip = GeoUtils.random_ipv4(ip_block)
-                if self.get_param('verbose', False):
-                    self.to_screen(
+                if self._downloader.params.get('verbose', False):
+                    self._downloader.to_screen(
                         '[debug] Using fake IP %s as X-Forwarded-For.'
                         % self._x_forwarded_for_ip)
                 return
@@ -548,7 +546,7 @@ class InfoExtractor(object):
 
             # Explicit country code specified by user, use it right away
             # regardless of whether extractor is geo bypassable or not
-            country = self.get_param('geo_bypass_country', None)
+            country = self._downloader.params.get('geo_bypass_country', None)
 
             # Otherwise use random country code from geo bypass context but
             # only if extractor is known as geo bypassable
@@ -559,8 +557,8 @@ class InfoExtractor(object):
 
             if country:
                 self._x_forwarded_for_ip = GeoUtils.random_ipv4(country)
-                if self.get_param('verbose', False):
-                    self.to_screen(
+                if self._downloader.params.get('verbose', False):
+                    self._downloader.to_screen(
                         '[debug] Using fake IP %s (%s) as X-Forwarded-For.'
                         % (self._x_forwarded_for_ip, country.upper()))
 
@@ -586,9 +584,9 @@ class InfoExtractor(object):
             raise ExtractorError('An extractor error has occurred.', cause=e)
 
     def __maybe_fake_ip_and_retry(self, countries):
-        if (not self.get_param('geo_bypass_country', None)
+        if (not self._downloader.params.get('geo_bypass_country', None)
                 and self._GEO_BYPASS
-                and self.get_param('geo_bypass', True)
+                and self._downloader.params.get('geo_bypass', True)
                 and not self._x_forwarded_for_ip
                 and countries):
             country_code = random.choice(countries)
@@ -698,7 +696,7 @@ class InfoExtractor(object):
             if fatal:
                 raise ExtractorError(errmsg, sys.exc_info()[2], cause=err)
             else:
-                self.report_warning(errmsg)
+                self._downloader.report_warning(errmsg)
                 return False
 
     def _download_webpage_handle(self, url_or_request, video_id, note=None, errnote=None, fatal=True, encoding=None, data=None, headers={}, query={}, expected_status=None):
@@ -770,11 +768,11 @@ class InfoExtractor(object):
             webpage_bytes = prefix + webpage_bytes
         if not encoding:
             encoding = self._guess_encoding_from_content(content_type, webpage_bytes)
-        if self.get_param('dump_intermediate_pages', False):
+        if self._downloader.params.get('dump_intermediate_pages', False):
             self.to_screen('Dumping request to ' + urlh.geturl())
             dump = base64.b64encode(webpage_bytes).decode('ascii')
-            self.to_screen(dump)
-        if self.get_param('write_pages', False):
+            self._downloader.to_screen(dump)
+        if self._downloader.params.get('write_pages', False):
             basen = '%s_%s' % (video_id, urlh.geturl())
             if len(basen) > 240:
                 h = '___' + hashlib.md5(basen.encode('utf-8')).hexdigest()
@@ -976,9 +974,19 @@ class InfoExtractor(object):
         """Print msg to screen, prefixing it with '[ie_name]'"""
         self._downloader.to_screen(self.__ie_msg(msg))
 
-    def write_debug(self, msg, only_once=False):
+    def write_debug(self, msg, only_once=False, _cache=[]):
         '''Log debug message or Print message to stderr'''
-        self._downloader.write_debug(self.__ie_msg(msg), only_once=only_once)
+        if not self.get_param('verbose', False):
+            return
+        message = '[debug] ' + self.__ie_msg(msg)
+        logger = self.get_param('logger')
+        if logger:
+            logger.debug(message)
+        else:
+            if only_once and hash(message) in _cache:
+                return
+            self._downloader.to_stderr(message)
+            _cache.append(hash(message))
 
     # name, default=None, *args, **kwargs
     def get_param(self, name, *args, **kwargs):
@@ -1074,7 +1082,7 @@ class InfoExtractor(object):
                 if mobj:
                     break
 
-        if not self.get_param('no_color') and compat_os_name != 'nt' and sys.stderr.isatty():
+        if not self._downloader.params.get('no_color') and compat_os_name != 'nt' and sys.stderr.isatty():
             _name = '\033[0;34m%s\033[0m' % name
         else:
             _name = name
@@ -1092,7 +1100,7 @@ class InfoExtractor(object):
         elif fatal:
             raise RegexNotFoundError('Unable to extract %s' % _name)
         else:
-            self.report_warning('unable to extract %s' % _name + bug_reports_message())
+            self._downloader.report_warning('unable to extract %s' % _name + bug_reports_message())
             return None
 
     def _search_json(self, start_pattern, string, name, video_id, **kwargs):
@@ -1162,7 +1170,7 @@ class InfoExtractor(object):
         username = None
         password = None
 
-        if self.get_param('usenetrc', False):
+        if self._downloader.params.get('usenetrc', False):
             try:
                 netrc_machine = netrc_machine or self._NETRC_MACHINE
                 info = netrc.netrc().authenticators(netrc_machine)
@@ -1173,7 +1181,7 @@ class InfoExtractor(object):
                     raise netrc.NetrcParseError(
                         'No authenticators for %s' % netrc_machine)
             except (AttributeError, IOError, netrc.NetrcParseError) as err:
-                self.report_warning(
+                self._downloader.report_warning(
                     'parsing .netrc: %s' % error_to_compat_str(err))
 
         return username, password
@@ -1210,10 +1218,10 @@ class InfoExtractor(object):
         """
         if self._downloader is None:
             return None
+        downloader_params = self._downloader.params
 
-        twofactor = self.get_param('twofactor')
-        if twofactor is not None:
-            return twofactor
+        if downloader_params.get('twofactor') is not None:
+            return downloader_params['twofactor']
 
         return compat_getpass('Type %s and press [Return]: ' % note)
 
@@ -1348,7 +1356,7 @@ class InfoExtractor(object):
         elif fatal:
             raise RegexNotFoundError('Unable to extract JSON-LD')
         else:
-            self.report_warning('unable to extract JSON-LD %s' % bug_reports_message())
+            self._downloader.report_warning('unable to extract JSON-LD %s' % bug_reports_message())
             return {}
 
     def _json_ld(self, json_ld, video_id, fatal=True, expected_type=None):
@@ -1579,7 +1587,7 @@ class InfoExtractor(object):
 
             if f.get('vcodec') == 'none':  # audio only
                 preference -= 50
-                if self.get_param('prefer_free_formats'):
+                if self._downloader.params.get('prefer_free_formats'):
                     ORDER = ['aac', 'mp3', 'm4a', 'webm', 'ogg', 'opus']
                 else:
                     ORDER = ['webm', 'opus', 'ogg', 'mp3', 'aac', 'm4a']
@@ -1591,7 +1599,7 @@ class InfoExtractor(object):
             else:
                 if f.get('acodec') == 'none':  # video only
                     preference -= 40
-                if self.get_param('prefer_free_formats'):
+                if self._downloader.params.get('prefer_free_formats'):
                     ORDER = ['flv', 'mp4', 'webm']
                 else:
                     ORDER = ['webm', 'flv', 'mp4']
@@ -1657,7 +1665,7 @@ class InfoExtractor(object):
         """ Either "http:" or "https:", depending on the user's preferences """
         return (
             'http:'
-            if self.get_param('prefer_insecure', False)
+            if self._downloader.params.get('prefer_insecure', False)
             else 'https:')
 
     def _proto_relative_url(self, url, scheme=None):
@@ -3162,7 +3170,7 @@ class InfoExtractor(object):
                     # See com/longtailvideo/jwplayer/media/RTMPMediaProvider.as
                     # of jwplayer.flash.swf
                     rtmp_url_parts = re.split(
-                        r'((?:mp4|mp3|flv):)', source_url, maxsplit=1)
+                        r'((?:mp4|mp3|flv):)', source_url, 1)
                     if len(rtmp_url_parts) == 3:
                         rtmp_url, prefix, play_path = rtmp_url_parts
                         a_format.update({
@@ -3189,7 +3197,7 @@ class InfoExtractor(object):
             if fatal:
                 raise ExtractorError(msg)
             else:
-                self.report_warning(msg)
+                self._downloader.report_warning(msg)
         return res
 
     def _float(self, v, name, fatal=False, **kwargs):
@@ -3199,7 +3207,7 @@ class InfoExtractor(object):
             if fatal:
                 raise ExtractorError(msg)
             else:
-                self.report_warning(msg)
+                self._downloader.report_warning(msg)
         return res
 
     def _set_cookie(self, domain, name, value, expire_time=None, port=None,
@@ -3208,12 +3216,12 @@ class InfoExtractor(object):
             0, name, value, port, port is not None, domain, True,
             domain.startswith('.'), path, True, secure, expire_time,
             discard, None, None, rest)
-        self.cookiejar.set_cookie(cookie)
+        self._downloader.cookiejar.set_cookie(cookie)
 
     def _get_cookies(self, url):
         """ Return a compat_cookies_SimpleCookie with the cookies for the url """
         req = sanitized_Request(url)
-        self.cookiejar.add_cookie_header(req)
+        self._downloader.cookiejar.add_cookie_header(req)
         return compat_cookies_SimpleCookie(req.get_header('Cookie'))
 
     def _apply_first_set_cookie_header(self, url_handle, cookie):
@@ -3273,8 +3281,8 @@ class InfoExtractor(object):
         return not any_restricted
 
     def extract_subtitles(self, *args, **kwargs):
-        if (self.get_param('writesubtitles', False)
-                or self.get_param('listsubtitles')):
+        if (self._downloader.params.get('writesubtitles', False)
+                or self._downloader.params.get('listsubtitles')):
             return self._get_subtitles(*args, **kwargs)
         return {}
 
@@ -3295,11 +3303,7 @@ class InfoExtractor(object):
         """ Merge subtitle dictionaries, language by language. """
 
         # ..., * , target=None
-        target = kwargs.get('target')
-        if target is None:
-            target = dict(subtitle_dict1)
-        else:
-            subtitle_dicts = (subtitle_dict1,) + subtitle_dicts
+        target = kwargs.get('target') or dict(subtitle_dict1)
 
         for subtitle_dict in subtitle_dicts:
             for lang in subtitle_dict:
@@ -3307,8 +3311,8 @@ class InfoExtractor(object):
         return target
 
     def extract_automatic_captions(self, *args, **kwargs):
-        if (self.get_param('writeautomaticsub', False)
-                or self.get_param('listsubtitles')):
+        if (self._downloader.params.get('writeautomaticsub', False)
+                or self._downloader.params.get('listsubtitles')):
             return self._get_automatic_captions(*args, **kwargs)
         return {}
 
@@ -3316,9 +3320,9 @@ class InfoExtractor(object):
         raise NotImplementedError('This method must be implemented by subclasses')
 
     def mark_watched(self, *args, **kwargs):
-        if (self.get_param('mark_watched', False)
+        if (self._downloader.params.get('mark_watched', False)
                 and (self._get_login_info()[0] is not None
-                     or self.get_param('cookiefile') is not None)):
+                     or self._downloader.params.get('cookiefile') is not None)):
             self._mark_watched(*args, **kwargs)
 
     def _mark_watched(self, *args, **kwargs):
@@ -3326,7 +3330,7 @@ class InfoExtractor(object):
 
     def geo_verification_headers(self):
         headers = {}
-        geo_verification_proxy = self.get_param('geo_verification_proxy')
+        geo_verification_proxy = self._downloader.params.get('geo_verification_proxy')
         if geo_verification_proxy:
             headers['Ytdl-request-proxy'] = geo_verification_proxy
         return headers
diff --git a/youtube_dl/extractor/itv.py b/youtube_dl/extractor/itv.py
index 2510ad887..c64af3be6 100644
--- a/youtube_dl/extractor/itv.py
+++ b/youtube_dl/extractor/itv.py
@@ -35,6 +35,15 @@ from ..utils import (
 
 class ITVBaseIE(InfoExtractor):
 
+    def _search_nextjs_data(self, webpage, video_id, **kw):
+        transform_source = kw.pop('transform_source', None)
+        fatal = kw.pop('fatal', True)
+        return self._parse_json(
+            self._search_regex(
+                r'''<script\b[^>]+\bid=('|")__NEXT_DATA__\1[^>]*>(?P<js>[^<]+)</script>''',
+                webpage, 'next.js data', group='js', fatal=fatal, **kw),
+            video_id, transform_source=transform_source, fatal=fatal)
+
     def __handle_request_webpage_error(self, err, video_id=None, errnote=None, fatal=True):
         if errnote is False:
             return False
@@ -100,9 +109,7 @@ class ITVBaseIE(InfoExtractor):
 
 class ITVIE(ITVBaseIE):
     _VALID_URL = r'https?://(?:www\.)?itv\.com/(?:(?P<w>watch)|hub)/[^/]+/(?(w)[\w-]+/)(?P<id>\w+)'
-    IE_DESC = 'ITVX'
-    _WORKING = False
-
+    _IE_DESC = 'ITVX'
     _TESTS = [{
         'note': 'Hub URLs redirect to ITVX',
         'url': 'https://www.itv.com/hub/liar/2a4547a0012',
@@ -263,7 +270,7 @@ class ITVIE(ITVBaseIE):
                 'ext': determine_ext(href, 'vtt'),
             })
 
-        next_data = self._search_nextjs_data(webpage, video_id, fatal=False, default={})
+        next_data = self._search_nextjs_data(webpage, video_id, fatal=False, default='{}')
         video_data.update(traverse_obj(next_data, ('props', 'pageProps', ('title', 'episode')), expected_type=dict)[0] or {})
         title = traverse_obj(video_data, 'headerTitle', 'episodeTitle')
         info = self._og_extract(webpage, require_title=not title)
@@ -316,7 +323,7 @@ class ITVIE(ITVBaseIE):
 
 class ITVBTCCIE(ITVBaseIE):
     _VALID_URL = r'https?://(?:www\.)?itv\.com/(?!(?:watch|hub)/)(?:[^/]+/)+(?P<id>[^/?#&]+)'
-    IE_DESC = 'ITV articles: News, British Touring Car Championship'
+    _IE_DESC = 'ITV articles: News, British Touring Car Championship'
     _TESTS = [{
         'note': 'British Touring Car Championship',
         'url': 'https://www.itv.com/btcc/articles/btcc-2018-all-the-action-from-brands-hatch',
diff --git a/youtube_dl/extractor/senateisvp.py b/youtube_dl/extractor/senateisvp.py
index b8ac58713..db5ef8b57 100644
--- a/youtube_dl/extractor/senateisvp.py
+++ b/youtube_dl/extractor/senateisvp.py
@@ -47,7 +47,7 @@ class SenateISVPIE(InfoExtractor):
         ['vetaff', '76462', 'http://vetaff-f.akamaihd.net'],
         ['arch', '', 'http://ussenate-f.akamaihd.net/']
     ]
-    IE_NAME = 'senate.gov'
+    _IE_NAME = 'senate.gov'
     _VALID_URL = r'https?://(?:www\.)?senate\.gov/isvp/?\?(?P<qs>.+)'
     _TESTS = [{
         'url': 'http://www.senate.gov/isvp/?comm=judiciary&type=live&stt=&filename=judiciary031715&auto_play=false&wmode=transparent&poster=http%3A%2F%2Fwww.judiciary.senate.gov%2Fthemes%2Fjudiciary%2Fimages%2Fvideo-poster-flash-fit.png',
diff --git a/youtube_dl/extractor/youtube.py b/youtube_dl/extractor/youtube.py
index b31798729..2e31a8979 100644
--- a/youtube_dl/extractor/youtube.py
+++ b/youtube_dl/extractor/youtube.py
@@ -3,14 +3,11 @@
 from __future__ import unicode_literals
 
 import collections
-import hashlib
 import itertools
 import json
 import os.path
 import random
 import re
-import string
-import time
 import traceback
 
 from .common import InfoExtractor, SearchInfoExtractor
@@ -27,14 +24,11 @@ from ..compat import (
 )
 from ..jsinterp import JSInterpreter
 from ..utils import (
-    bug_reports_message,
     clean_html,
     dict_get,
     error_to_compat_str,
     ExtractorError,
-    filter_dict,
     float_or_none,
-    get_first,
     extract_attributes,
     get_element_by_attribute,
     int_or_none,
@@ -49,7 +43,6 @@ from ..utils import (
     parse_duration,
     parse_qs,
     qualities,
-    remove_end,
     remove_start,
     smuggle_url,
     str_or_none,
@@ -67,13 +60,11 @@ from ..utils import (
     url_or_none,
     urlencode_postdata,
     urljoin,
-    variadic,
 )
 
 
 class YoutubeBaseInfoExtractor(InfoExtractor):
     """Provide base functions for Youtube extractors"""
-
     _LOGIN_URL = 'https://accounts.google.com/ServiceLogin'
     _TWOFACTOR_URL = 'https://accounts.google.com/signin/challenge'
 
@@ -87,66 +78,9 @@ class YoutubeBaseInfoExtractor(InfoExtractor):
 
     _PLAYLIST_ID_RE = r'(?:(?:PL|LL|EC|UU|FL|RD|UL|TL|PU|OLAK5uy_)[0-9A-Za-z-_]{10,}|RDMM)'
 
-    _INNERTUBE_CLIENTS = {
-        'ios': {
-            'INNERTUBE_CONTEXT': {
-                'client': {
-                    'clientName': 'IOS',
-                    'clientVersion': '20.10.4',
-                    'deviceMake': 'Apple',
-                    'deviceModel': 'iPhone16,2',
-                    'userAgent': 'com.google.ios.youtube/20.10.4 (iPhone16,2; U; CPU iOS 18_3_2 like Mac OS X;)',
-                    'osName': 'iPhone',
-                    'osVersion': '18.3.2.22D82',
-                },
-            },
-            'INNERTUBE_CONTEXT_CLIENT_NAME': 5,
-            'REQUIRE_JS_PLAYER': False,
-            'REQUIRE_PO_TOKEN': True,
-        },
-        # mweb has 'ultralow' formats
-        # See: https://github.com/yt-dlp/yt-dlp/pull/557
-        'mweb': {
-            'INNERTUBE_CONTEXT': {
-                'client': {
-                    'clientName': 'MWEB',
-                    'clientVersion': '2.20250311.03.00',
-                    # mweb previously did not require PO Token with this UA
-                    'userAgent': 'Mozilla/5.0 (iPad; CPU OS 16_7_10 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/16.6 Mobile/15E148 Safari/604.1,gzip(gfe)',
-                },
-            },
-            'INNERTUBE_CONTEXT_CLIENT_NAME': 2,
-            'REQUIRE_PO_TOKEN': True,
-            'SUPPORTS_COOKIES': True,
-        },
-        'tv': {
-            'INNERTUBE_CONTEXT': {
-                'client': {
-                    'clientName': 'TVHTML5',
-                    'clientVersion': '7.20250312.16.00',
-                    'userAgent': 'Mozilla/5.0 (ChromiumStylePlatform) Cobalt/Version',
-                },
-            },
-            'INNERTUBE_CONTEXT_CLIENT_NAME': 7,
-            'SUPPORTS_COOKIES': True,
-        },
-        'web': {
-            'INNERTUBE_CONTEXT': {
-                'client': {
-                    'clientName': 'WEB',
-                    'clientVersion': '2.20250312.04.00',
-                },
-            },
-            'INNERTUBE_CONTEXT_CLIENT_NAME': 1,
-            'REQUIRE_PO_TOKEN': True,
-            'SUPPORTS_COOKIES': True,
-        },
-    }
-
     def _login(self):
         """
         Attempt to log in to YouTube.
-
         True is returned if successful or skipped.
         False is returned if login failed.
 
@@ -202,7 +136,7 @@ class YoutubeBaseInfoExtractor(InfoExtractor):
                 [2, 1, None, 1,
                  'https://accounts.google.com/ServiceLogin?passive=true&continue=https%3A%2F%2Fwww.youtube.com%2Fsignin%3Fnext%3D%252F%26action_handle_signin%3Dtrue%26hl%3Den%26app%3Ddesktop%26feature%3Dsign_in_button&hl=en&service=youtube&uilel=3&requestPath=%2FServiceLogin&Page=PasswordSeparationSignIn',
                  None, [], 4],
-                1, [None, None, []], None, None, None, True,
+                1, [None, None, []], None, None, None, True
             ],
             username,
         ]
@@ -224,7 +158,7 @@ class YoutubeBaseInfoExtractor(InfoExtractor):
             None, 1, None, [1, None, None, None, [password, None, True]],
             [
                 None, None, [2, 1, None, 1, 'https://accounts.google.com/ServiceLogin?passive=true&continue=https%3A%2F%2Fwww.youtube.com%2Fsignin%3Fnext%3D%252F%26action_handle_signin%3Dtrue%26hl%3Den%26app%3Ddesktop%26feature%3Dsign_in_button&hl=en&service=youtube&uilel=3&requestPath=%2FServiceLogin&Page=PasswordSeparationSignIn', None, [], 4],
-                1, [None, None, []], None, None, None, True,
+                1, [None, None, []], None, None, None, True
             ]]
 
         challenge_results = req(
@@ -277,7 +211,7 @@ class YoutubeBaseInfoExtractor(InfoExtractor):
                     user_hash, None, 2, None,
                     [
                         9, None, None, None, None, None, None, None,
-                        [None, tfa_code, True, 2],
+                        [None, tfa_code, True, 2]
                     ]]
 
                 tfa_results = req(
@@ -343,57 +277,32 @@ class YoutubeBaseInfoExtractor(InfoExtractor):
         if not self._login():
             return
 
-    _DEFAULT_API_DATA = {'context': _INNERTUBE_CLIENTS['web']['INNERTUBE_CONTEXT']}
+    _DEFAULT_API_DATA = {
+        'context': {
+            'client': {
+                'clientName': 'WEB',
+                'clientVersion': '2.20201021.03.00',
+            }
+        },
+    }
 
     _YT_INITIAL_DATA_RE = r'(?:window\s*\[\s*["\']ytInitialData["\']\s*\]|ytInitialData)\s*=\s*({.+?})\s*;'
     _YT_INITIAL_PLAYER_RESPONSE_RE = r'ytInitialPlayerResponse\s*=\s*({.+?})\s*;'
     _YT_INITIAL_BOUNDARY_RE = r'(?:var\s+meta|</script|\n)'
 
-    _SAPISID = None
-
-    def _generate_sapisidhash_header(self, origin='https://www.youtube.com'):
-        time_now = round(time.time())
-        if self._SAPISID is None:
-            yt_cookies = self._get_cookies('https://www.youtube.com')
-            # Sometimes SAPISID cookie isn't present but __Secure-3PAPISID is.
-            # See: https://github.com/yt-dlp/yt-dlp/issues/393
-            sapisid_cookie = dict_get(
-                yt_cookies, ('__Secure-3PAPISID', 'SAPISID'))
-            if sapisid_cookie and sapisid_cookie.value:
-                self._SAPISID = sapisid_cookie.value
-                self.write_debug('Extracted SAPISID cookie')
-                # SAPISID cookie is required if not already present
-                if not yt_cookies.get('SAPISID'):
-                    self.write_debug('Copying __Secure-3PAPISID cookie to SAPISID cookie')
-                    self._set_cookie(
-                        '.youtube.com', 'SAPISID', self._SAPISID, secure=True, expire_time=time_now + 3600)
-            else:
-                self._SAPISID = False
-        if not self._SAPISID:
-            return None
-        # SAPISIDHASH algorithm from https://stackoverflow.com/a/32065323
-        sapisidhash = hashlib.sha1(
-            '{0} {1} {2}'.format(time_now, self._SAPISID, origin).encode('utf-8')).hexdigest()
-        return 'SAPISIDHASH {0}_{1}'.format(time_now, sapisidhash)
-
-    def _call_api(self, ep, query, video_id, fatal=True, headers=None,
-                  note='Downloading API JSON'):
+    def _call_api(self, ep, query, video_id, fatal=True, headers=None):
         data = self._DEFAULT_API_DATA.copy()
         data.update(query)
         real_headers = {'content-type': 'application/json'}
         if headers:
             real_headers.update(headers)
 
-        # was: 'AIzaSyAO_FJ2SlqU8Q4STEHLGCilw_Y9_11qcW8'
-        api_key = self.get_param('youtube_innertube_key')
         return self._download_json(
             'https://www.youtube.com/youtubei/v1/%s' % ep, video_id=video_id,
-            note=note, errnote='Unable to download API page',
+            note='Downloading API JSON', errnote='Unable to download API page',
             data=json.dumps(data).encode('utf8'), fatal=fatal,
-            headers=real_headers, query=filter_dict({
-                'key': api_key,
-                'prettyPrint': 'false',
-            }))
+            headers=real_headers,
+            query={'key': 'AIzaSyAO_FJ2SlqU8Q4STEHLGCilw_Y9_11qcW8'})
 
     def _extract_yt_initial_data(self, video_id, webpage):
         return self._parse_json(
@@ -402,22 +311,6 @@ class YoutubeBaseInfoExtractor(InfoExtractor):
                  self._YT_INITIAL_DATA_RE), webpage, 'yt initial data'),
             video_id)
 
-    def _extract_visitor_data(self, *args):
-        """
-        Extract visitorData from an API response or ytcfg
-
-        Appears to be used to track session state
-        """
-        visitor_data = self.get_param('youtube_visitor_data')
-        if visitor_data:
-            return visitor_data
-
-        return get_first(
-            args, (('VISITOR_DATA',
-                    ('INNERTUBE_CONTEXT', 'client', 'visitorData'),
-                    ('responseContext', 'visitorData')),
-                   T(compat_str)))
-
     def _extract_ytcfg(self, video_id, webpage):
         return self._parse_json(
             self._search_regex(
@@ -457,33 +350,13 @@ class YoutubeBaseInfoExtractor(InfoExtractor):
             'uploader': uploader,
         }
 
-    @staticmethod
-    def _extract_thumbnails(data, *path_list, **kw_final_key):
-        """
-        Extract thumbnails from thumbnails dict
-        @param path_list: path list to level that contains 'thumbnails' key
-        """
-        final_key = kw_final_key.get('final_key', 'thumbnails')
-
-        return traverse_obj(data, ((
-            tuple(variadic(path) + (final_key, Ellipsis)
-                  for path in path_list or [()])), {
-            'url': ('url', T(url_or_none),
-                    # Sometimes youtube gives a wrong thumbnail URL. See:
-                    # https://github.com/yt-dlp/yt-dlp/issues/233
-                    # https://github.com/ytdl-org/youtube-dl/issues/28023
-                    T(lambda u: update_url(u, query=None) if u and 'maxresdefault' in u else u)),
-            'height': ('height', T(int_or_none)),
-            'width': ('width', T(int_or_none)),
-        }, T(lambda t: t if t.get('url') else None)))
-
     def _search_results(self, query, params):
         data = {
             'context': {
                 'client': {
                     'clientName': 'WEB',
                     'clientVersion': '2.20201021.03.00',
-                },
+                }
             },
             'query': query,
         }
@@ -491,15 +364,11 @@ class YoutubeBaseInfoExtractor(InfoExtractor):
             data['params'] = params
         for page_num in itertools.count(1):
             search = self._download_json(
-                'https://www.youtube.com/youtubei/v1/search',
+                'https://www.youtube.com/youtubei/v1/search?key=AIzaSyAO_FJ2SlqU8Q4STEHLGCilw_Y9_11qcW8',
                 video_id='query "%s"' % query,
                 note='Downloading page %s' % page_num,
                 errnote='Unable to download API page', fatal=False,
                 data=json.dumps(data).encode('utf8'),
-                query={
-                    # 'key': 'AIzaSyAO_FJ2SlqU8Q4STEHLGCilw_Y9_11qcW8',
-                    'prettyPrint': 'false',
-                },
                 headers={'content-type': 'application/json'})
             if not search:
                 break
@@ -564,7 +433,7 @@ class YoutubeBaseInfoExtractor(InfoExtractor):
             #       (HTML, videodetails, metadata, renderers)
             'name': ('content', 'author', (('ownerChannelName', None), 'title'), ['text']),
             'url': ('href', 'ownerProfileUrl', 'vanityChannelUrl',
-                    ['navigationEndpoint', 'browseEndpoint', 'canonicalBaseUrl']),
+                    ['navigationEndpoint', 'browseEndpoint', 'canonicalBaseUrl'])
         }
         if any((videodetails, metadata, renderers)):
             result = (
@@ -690,9 +559,9 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
         'invidious': '|'.join(_INVIDIOUS_SITES),
     }
     _PLAYER_INFO_RE = (
-        r'/s/player/(?P<id>[a-zA-Z0-9_-]{8,})/(?:tv-)?player',
-        r'/(?P<id>[a-zA-Z0-9_-]{8,})/player(?:_ias(?:_tce)?\.vflset(?:/[a-zA-Z]{2,3}_[a-zA-Z]{2,3})?|-plasma-ias-(?:phone|tablet)-[a-z]{2}_[A-Z]{2}\.vflset)/base\.js$',
-        r'\b(?P<id>vfl[a-zA-Z0-9_-]{6,})\b.*?\.js$',
+        r'/s/player/(?P<id>[a-zA-Z0-9_-]{8,})/player',
+        r'/(?P<id>[a-zA-Z0-9_-]{8,})/player(?:_ias\.vflset(?:/[a-zA-Z]{2,3}_[a-zA-Z]{2,3})?|-plasma-ias-(?:phone|tablet)-[a-z]{2}_[A-Z]{2}\.vflset)/base\.js$',
+        r'\b(?P<id>vfl[a-zA-Z0-9_-]+)\b.*?\.js$',
     )
     _SUBTITLE_FORMATS = ('json3', 'srv1', 'srv2', 'srv3', 'ttml', 'vtt')
 
@@ -773,7 +642,7 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
                 'uploader_url': r're:https?://(?:www\.)?youtube\.com/user/8KVIDEO',
                 'description': '',
                 'uploader': '8KVIDEO',
-                'title': 'UHDTV TEST 8K VIDEO.mp4',
+                'title': 'UHDTV TEST 8K VIDEO.mp4'
             },
             'params': {
                 'youtube_include_dash_manifest': True,
@@ -813,7 +682,7 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
                 'uploader_url': r're:https?://(?:www\.)?youtube\.com/@theamazingatheist',
                 'title': 'Burning Everyone\'s Koran',
                 'description': 'SUBSCRIBE: http://www.youtube.com/saturninefilms \r\n\r\nEven Obama has taken a stand against freedom on this issue: http://www.huffingtonpost.com/2010/09/09/obama-gma-interview-quran_n_710282.html',
-            },
+            }
         },
         # Age-gated videos
         {
@@ -941,7 +810,7 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
             },
             'expected_warnings': [
                 'DASH manifest missing',
-            ],
+            ]
         },
         # Olympics (https://github.com/ytdl-org/youtube-dl/issues/4431)
         {
@@ -1585,15 +1454,6 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
         '397': {'acodec': 'none', 'vcodec': 'av01.0.05M.08'},
     }
 
-    _PLAYER_JS_VARIANT_MAP = (
-        ('main', 'player_ias.vflset/en_US/base.js'),
-        ('tce', 'player_ias_tce.vflset/en_US/base.js'),
-        ('tv', 'tv-player-ias.vflset/tv-player-ias.js'),
-        ('tv_es6', 'tv-player-es6.vflset/tv-player-es6.js'),
-        ('phone', 'player-plasma-ias-phone-en_US.vflset/base.js'),
-        ('tablet', 'player-plasma-ias-tablet-en_US.vflset/base.js'),
-    )
-
     @classmethod
     def suitable(cls, url):
         if parse_qs(url).get('list', [None])[0]:
@@ -1633,97 +1493,46 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
         """ Return a string representation of a signature """
         return '.'.join(compat_str(len(part)) for part in example_sig.split('.'))
 
-    def _extract_player_info(self, player_url):
-        try:
-            return self._search_regex(
-                self._PLAYER_INFO_RE, player_url, 'player info', group='id')
-        except ExtractorError as e:
-            raise ExtractorError(
-                'Cannot identify player %r' % (player_url,), cause=e)
+    @classmethod
+    def _extract_player_info(cls, player_url):
+        for player_re in cls._PLAYER_INFO_RE:
+            id_m = re.search(player_re, player_url)
+            if id_m:
+                break
+        else:
+            raise ExtractorError('Cannot identify player %r' % player_url)
+        return id_m.group('id')
 
-    def _player_js_cache_key(self, player_url, extra_id=None, _cache={}):
-        if player_url not in _cache:
+    def _load_player(self, video_id, player_url, fatal=True, player_id=None):
+        if not player_id:
             player_id = self._extract_player_info(player_url)
-            player_path = remove_start(
-                compat_urllib_parse.urlparse(player_url).path,
-                '/s/player/{0}/'.format(player_id))
-            variant = next((k for k, v in self._PLAYER_JS_VARIANT_MAP
-                           if v == player_path), None)
-            if not variant:
-                variant = next(
-                    (k for k, v in self._PLAYER_JS_VARIANT_MAP
-                     if re.match(re.escape(v).replace('en_US', r'\w+') + '$', player_path)),
-                    None)
-            if not variant:
-                self.write_debug(
-                    'Unable to determine player JS variant\n'
-                    '        player = {0}'.format(player_url), only_once=True)
-                variant = re.sub(r'[^a-zA-Z0-9]', '_', remove_end(player_path, '.js'))
-            _cache[player_url] = join_nonempty(player_id, variant)
-
-        if extra_id:
-            extra_id = '-'.join((_cache[player_url], extra_id))
-            assert os.path.basename(extra_id) == extra_id
-            return extra_id
-        return _cache[player_url]
-
-    def _load_player(self, video_id, player_url, fatal=True):
-        player_js_key = self._player_js_cache_key(player_url)
-        if player_js_key not in self._code_cache:
+        if player_id not in self._code_cache:
             code = self._download_webpage(
                 player_url, video_id, fatal=fatal,
-                note='Downloading player {0}'.format(player_js_key),
-                errnote='Download of {0} failed'.format(player_url))
+                note='Downloading player ' + player_id,
+                errnote='Download of %s failed' % player_url)
             if code:
-                self._code_cache[player_js_key] = code
-        return self._code_cache.get(player_js_key)
-
-    def _load_player_data_from_cache(self, name, player_url, extra_id=None):
-        cache_id = ('youtube-{0}'.format(name), self._player_js_cache_key(player_url, extra_id))
-        data = self._player_cache.get(cache_id)
-        if data:
-            return data
-
-        data = self.cache.load(*cache_id, min_ver='2025.04.07')
-        if data:
-            self._player_cache[cache_id] = data
-        return data
-
-    def _store_player_data_to_cache(self, name, player_url, data, extra_id=None):
-        cache_id = ('youtube-{0}'.format(name), self._player_js_cache_key(player_url, extra_id))
-
-        if cache_id not in self._player_cache:
-            self.cache.store(cache_id[0], cache_id[1], data)
-            self._player_cache[cache_id] = data
-
-    def _remove_player_data_from_cache(self, name, player_url, extra_id=None):
-        cache_id = ('youtube-{0}'.format(name), self._player_js_cache_key(player_url, extra_id))
-
-        if cache_id in self._player_cache:
-            self.cache.clear(*cache_id)
-            self._player_cache.pop(cache_id, None)
+                self._code_cache[player_id] = code
+        return self._code_cache[player_id] if fatal else self._code_cache.get(player_id)
 
     def _extract_signature_function(self, video_id, player_url, example_sig):
-        # player_id = self._extract_player_info(player_url)
+        player_id = self._extract_player_info(player_url)
 
         # Read from filesystem cache
-        extra_id = self._signature_cache_id(example_sig)
-        self.write_debug('Extracting signature function {0}-{1}'.format(player_url, extra_id))
-        cache_spec, code = self._load_player_data_from_cache(
-            'sigfuncs', player_url, extra_id=extra_id), None
+        func_id = 'js_{0}_{1}'.format(
+            player_id, self._signature_cache_id(example_sig))
+        assert os.path.basename(func_id) == func_id
+
+        self.write_debug('Extracting signature function {0}'.format(func_id))
+        cache_spec, code = self.cache.load('youtube-sigfuncs', func_id), None
 
         if not cache_spec:
-            code = self._load_player(video_id, player_url)
-            if code:
-                res = self._parse_sig_js(code)
-                test_string = ''.join(map(compat_chr, range(len(example_sig))))
-                cache_spec = [ord(c) for c in res(test_string)]
-                self._store_player_data_to_cache(
-                    'sigfuncs', player_url, cache_spec, extra_id=extra_id)
-            else:
-                self.report_warning(
-                    'Failed to compute signature function {0}-{1}'.format(
-                        player_url, extra_id))
+            code = self._load_player(video_id, player_url, player_id)
+        if code:
+            res = self._parse_sig_js(code)
+            test_string = ''.join(map(compat_chr, range(len(example_sig))))
+            cache_spec = [ord(c) for c in res(test_string)]
+            self.cache.store('youtube-sigfuncs', func_id, cache_spec)
 
         return lambda s: ''.join(s[i] for i in cache_spec)
 
@@ -1769,54 +1578,26 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
                 '    return %s\n') % (signature_id_tuple, expr_code)
         self.to_screen('Extracted signature function:\n' + code)
 
-    def _extract_sig_fn(self, jsi, funcname):
-        var_ay = self._search_regex(
-            r'''(?x)
-                (?:\*/|\{|\n|^)\s*(?:'[^']+'\s*;\s*)
-                    (var\s*[\w$]+\s*=\s*(?:
-                        ('|")(?:\\\2|(?!\2).)+\2\s*\.\s*split\(\s*('|")\W+\3\s*\)|
-                        \[\s*(?:('|")(?:\\\4|(?!\4).)*\4\s*(?:(?=\])|,\s*))+\]
-                    ))(?=\s*[,;])
-            ''', jsi.code, 'useful values', default='')
-
-        sig_fn = jsi.extract_function_code(funcname)
-
-        if var_ay:
-            sig_fn = (sig_fn[0], ';\n'.join((var_ay, sig_fn[1])))
-
-        return sig_fn
-
     def _parse_sig_js(self, jscode):
-        # Examples where `sig` is funcname:
-        # sig=function(a){a=a.split(""); ... ;return a.join("")};
-        # ;c&&(c=sig(decodeURIComponent(c)),a.set(b,encodeURIComponent(c)));return a};
-        # {var l=f,m=h.sp,n=sig(decodeURIComponent(h.s));l.set(m,encodeURIComponent(n))}
-        # sig=function(J){J=J.split(""); ... ;return J.join("")};
-        # ;N&&(N=sig(decodeURIComponent(N)),J.set(R,encodeURIComponent(N)));return J};
-        # {var H=u,k=f.sp,v=sig(decodeURIComponent(f.s));H.set(k,encodeURIComponent(v))}
         funcname = self._search_regex(
-            (r'\b(?P<var>[\w$]+)&&\((?P=var)=(?P<sig>[\w$]{2,})\(decodeURIComponent\((?P=var)\)\)',
-             r'(?P<sig>[\w$]+)\s*=\s*function\(\s*(?P<arg>[\w$]+)\s*\)\s*{\s*(?P=arg)\s*=\s*(?P=arg)\.split\(\s*""\s*\)\s*;\s*[^}]+;\s*return\s+(?P=arg)\.join\(\s*""\s*\)',
-             r'(?:\b|[^\w$])(?P<sig>[\w$]{2,})\s*=\s*function\(\s*a\s*\)\s*{\s*a\s*=\s*a\.split\(\s*""\s*\)(?:;[\w$]{2}\.[\w$]{2}\(a,\d+\))?',
-             # Old patterns
-             r'\b[cs]\s*&&\s*[adf]\.set\([^,]+\s*,\s*encodeURIComponent\s*\(\s*(?P<sig>[\w$]+)\(',
-             r'\b[\w]+\s*&&\s*[\w]+\.set\([^,]+\s*,\s*encodeURIComponent\s*\(\s*(?P<sig>[\w$]+)\(',
-             r'\bm=(?P<sig>[\w$]{2,})\(decodeURIComponent\(h\.s\)\)',
+            (r'\b[cs]\s*&&\s*[adf]\.set\([^,]+\s*,\s*encodeURIComponent\s*\(\s*(?P<sig>[a-zA-Z0-9$]+)\(',
+             r'\b[a-zA-Z0-9]+\s*&&\s*[a-zA-Z0-9]+\.set\([^,]+\s*,\s*encodeURIComponent\s*\(\s*(?P<sig>[a-zA-Z0-9$]+)\(',
+             r'\bm=(?P<sig>[a-zA-Z0-9$]{2,})\(decodeURIComponent\(h\.s\)\)',
+             r'\bc&&\(c=(?P<sig>[a-zA-Z0-9$]{2,})\(decodeURIComponent\(c\)\)',
+             r'(?:\b|[^a-zA-Z0-9$])(?P<sig>[a-zA-Z0-9$]{2,})\s*=\s*function\(\s*a\s*\)\s*{\s*a\s*=\s*a\.split\(\s*""\s*\)(?:;[a-zA-Z0-9$]{2}\.[a-zA-Z0-9$]{2}\(a,\d+\))?',
+             r'(?P<sig>[a-zA-Z0-9$]+)\s*=\s*function\(\s*a\s*\)\s*{\s*a\s*=\s*a\.split\(\s*""\s*\)',
              # Obsolete patterns
-             r'("|\')signature\1\s*,\s*(?P<sig>[\w$]+)\(',
-             r'\.sig\|\|(?P<sig>[\w$]+)\(',
-             r'yt\.akamaized\.net/\)\s*\|\|\s*.*?\s*[cs]\s*&&\s*[adf]\.set\([^,]+\s*,\s*(?:encodeURIComponent\s*\()?\s*(?P<sig>[\w$]+)\(',
-             r'\b[cs]\s*&&\s*[adf]\.set\([^,]+\s*,\s*(?P<sig>[\w$]+)\(',
-             r'\bc\s*&&\s*[\w]+\.set\([^,]+\s*,\s*\([^)]*\)\s*\(\s*(?P<sig>[\w$]+)\('),
+             r'("|\')signature\1\s*,\s*(?P<sig>[a-zA-Z0-9$]+)\(',
+             r'\.sig\|\|(?P<sig>[a-zA-Z0-9$]+)\(',
+             r'yt\.akamaized\.net/\)\s*\|\|\s*.*?\s*[cs]\s*&&\s*[adf]\.set\([^,]+\s*,\s*(?:encodeURIComponent\s*\()?\s*(?P<sig>[a-zA-Z0-9$]+)\(',
+             r'\b[cs]\s*&&\s*[adf]\.set\([^,]+\s*,\s*(?P<sig>[a-zA-Z0-9$]+)\(',
+             r'\b[a-zA-Z0-9]+\s*&&\s*[a-zA-Z0-9]+\.set\([^,]+\s*,\s*(?P<sig>[a-zA-Z0-9$]+)\(',
+             r'\bc\s*&&\s*[a-zA-Z0-9]+\.set\([^,]+\s*,\s*\([^)]*\)\s*\(\s*(?P<sig>[a-zA-Z0-9$]+)\('),
             jscode, 'Initial JS player signature function name', group='sig')
 
         jsi = JSInterpreter(jscode)
-
-        initial_function = self._extract_sig_fn(jsi, funcname)
-
-        func = jsi.extract_function_from_code(*initial_function)
-
-        return lambda s: func([s])
+        initial_function = jsi.extract_function(funcname)
+        return lambda s: initial_function([s])
 
     def _cached(self, func, *cache_id):
         def inner(*args, **kwargs):
@@ -1866,7 +1647,7 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
         except JSInterpreter.Exception as e:
             self.report_warning(
                 '%s (%s %s)' % (
-                    'Unable to decode n-parameter: expect download to be blocked or throttled',
+                    'Unable to decode n-parameter: download likely to be throttled',
                     error_to_compat_str(e),
                     traceback.format_exc()),
                 video_id=video_id)
@@ -1876,103 +1657,37 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
         return ret
 
     def _extract_n_function_name(self, jscode):
-        func_name, idx = None, None
-
-        def generic_n_function_search(func_name=None):
-            return self._search_regex(
-                r'''(?xs)
-                    (?:(?<=[^\w$])|^)       # instead of \b, which ignores $
-                    (?P<name>%s)\s*=\s*function\((?!\d)[a-zA-Z\d_$]+\)
-                    \s*\{(?:(?!};).)+?(?:
-                        ["']enhanced_except_ |
-                        return\s*(?P<q>"|')[a-zA-Z\d-]+_w8_(?P=q)\s*\+\s*[\w$]+
-                    )
-                ''' % (func_name or r'(?!\d)[a-zA-Z\d_$]+',), jscode,
-                'Initial JS player n function name', group='name',
-                default=None if func_name else NO_DEFAULT)
-
-        # these special cases are redundant and probably obsolete (2025-04):
-        # they make the tests run ~10% faster without fallback warnings
-        r"""
         func_name, idx = self._search_regex(
-            # (y=NuD(),Mw(k),q=k.Z[y]||null)&&(q=narray[idx](q),k.set(y,q),k.V||NuD(''))}};
-            # (R="nn"[+J.Z],mW(J),N=J.K[R]||null)&&(N=narray[idx](N),J.set(R,N))}};
-            # or:  (b=String.fromCharCode(110),c=a.get(b))&&c=narray[idx](c)
-            # or:  (b="nn"[+a.D],c=a.get(b))&&(c=narray[idx](c)
-            # or:  (PL(a),b=a.j.n||null)&&(b=narray[idx](b)
-            # or:  (b="nn"[+a.D],vL(a),c=a.j[b]||null)&&(c=narray[idx](c),a.set(b,c),narray.length||nfunc("")
-            # old: (b=a.get("n"))&&(b=narray[idx](b)(?P<c>[a-z])\s*=\s*[a-z]\s*
-            # older: (b=a.get("n"))&&(b=nfunc(b)
+            # new: (b=String.fromCharCode(110),c=a.get(b))&&c=nfunc[idx](c)
+            # old: .get("n"))&&(b=nfunc[idx](b)
+            # older: .get("n"))&&(b=nfunc(b)
             r'''(?x)
-                # (expr, ...,
-                \((?:(?:\s*[\w$]+\s*=)?(?:[\w$"+\.\s(\[]+(?:[)\]]\s*)?),)*
-                  # b=...
-                  (?P<b>[\w$]+)\s*=\s*(?!(?P=b)[^\w$])[\w$]+\s*(?:(?:
-                    \.\s*[\w$]+ |
-                    \[\s*[\w$]+\s*\] |
-                    \.\s*get\s*\(\s*[\w$"]+\s*\)
-                  )\s*){,2}(?:\s*\|\|\s*null(?=\s*\)))?\s*
-                \)\s*&&\s*\(        # ...)&&(
-                # b = nfunc, b = narray[idx]
-                (?P=b)\s*=\s*(?P<nfunc>[\w$]+)\s*
-                    (?:\[\s*(?P<idx>[\w$]+)\s*\]\s*)?
-                    # (...)
-                    \(\s*[\w$]+\s*\)
-            ''', jscode, 'Initial JS player n function name', group=('nfunc', 'idx'),
-            default=(None, None))
-        """
-
-        if not func_name:
-            # nfunc=function(x){...}|function nfunc(x); ...
-            # ... var y=[nfunc]|y[idx]=nfunc);
-            # obvious REs hang, so use a two-stage tactic
-            for m in re.finditer(r'''(?x)
-                    [\n;]var\s(?:(?:(?!,).)+,|\s)*?(?!\d)[\w$]+(?:\[(?P<idx>\d+)\])?\s*=\s*
-                        (?(idx)|\[\s*)(?P<nfunc>(?!\d)[\w$]+)(?(idx)|\s*\])
-                    \s*?[;\n]
-                    ''', jscode):
-                fn = self._search_regex(
-                    r'[;,]\s*(function\s+)?({0})(?(1)|\s*=\s*function)\s*\((?!\d)[\w$]+\)\s*\{1}(?!\s*return\s)'.format(
-                        re.escape(m.group('nfunc')), '{'),
-                    jscode, 'Initial JS player n function name (2)', group=2, default=None)
-                if fn:
-                    func_name = fn
-                    idx = m.group('idx')
-                    if generic_n_function_search(func_name):
-                        # don't look any further
-                        break
-
-        # thx bashonly: yt-dlp/yt-dlp/pull/10611
-        if not func_name:
-            self.report_warning('Falling back to generic n function search', only_once=True)
-            return generic_n_function_search()
-
+                (?:\(\s*(?P<b>[a-z])\s*=\s*String\s*\.\s*fromCharCode\s*\(\s*110\s*\)\s*,(?P<c>[a-z])\s*=\s*[a-z]\s*)?
+                \.\s*get\s*\(\s*(?(b)(?P=b)|"n")(?:\s*\)){2}\s*&&\s*\(\s*(?(c)(?P=c)|b)\s*=\s*
+                (?P<nfunc>[a-zA-Z_$][\w$]*)(?:\s*\[(?P<idx>\d+)\])?\s*\(\s*[\w$]+\s*\)
+            ''', jscode, 'Initial JS player n function name', group=('nfunc', 'idx'))
         if not idx:
             return func_name
 
-        return self._search_json(
-            r'(?<![\w-])var\s(?:(?:(?!,).)+,|\s)*?{0}\s*='.format(re.escape(func_name)), jscode,
-            'Initial JS player n function list ({0}.{1})'.format(func_name, idx),
-            func_name, contains_pattern=r'\[.+\]', end_pattern='[,;]',
-            transform_source=js_to_json)[int(idx)]
+        return self._parse_json(self._search_regex(
+            r'var {0}\s*=\s*(\[.+?\])\s*[,;]'.format(re.escape(func_name)), jscode,
+            'Initial JS player n function list ({0}.{1})'.format(func_name, idx)),
+            func_name, transform_source=js_to_json)[int(idx)]
 
     def _extract_n_function_code(self, video_id, player_url):
         player_id = self._extract_player_info(player_url)
-        func_code = self._load_player_data_from_cache('nsig', player_url)
+        func_code = self.cache.load('youtube-nsig', player_id)
         jscode = func_code or self._load_player(video_id, player_url)
         jsi = JSInterpreter(jscode)
 
         if func_code:
             return jsi, player_id, func_code
 
-        return self._extract_n_function_code_jsi(video_id, jsi, player_id, player_url)
+        func_name = self._extract_n_function_name(jscode)
 
-    def _extract_n_function_code_jsi(self, video_id, jsi, player_id=None, player_url=None):
-        func_name = self._extract_n_function_name(jsi.code)
+        func_code = jsi.extract_function_code(func_name)
 
-        func_code = self._extract_sig_fn(jsi, func_name)
-        if player_url:
-            self._store_player_data_to_cache('nsig', player_url, func_code)
+        self.cache.store('youtube-nsig', player_id, func_code)
         return jsi, player_id, func_code
 
     def _extract_n_function_from_code(self, jsi, func_code):
@@ -1980,13 +1695,13 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
 
         def extract_nsig(s):
             try:
-                ret = func([s], kwargs={'_ytdl_do_not_return': s})
+                ret = func([s])
             except JSInterpreter.Exception:
                 raise
             except Exception as e:
                 raise JSInterpreter.Exception(traceback.format_exc(), cause=e)
 
-            if ret.startswith('enhanced_except_') or ret.endswith(s):
+            if ret.startswith('enhanced_except_'):
                 raise JSInterpreter.Exception('Signature function returned an exception')
             return ret
 
@@ -2005,8 +1720,7 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
             n_param = n_param[-1]
             n_response = decrypt_nsig(n_param)(n_param, video_id, player_url)
             if n_response is None:
-                # give up and forget cached data if descrambling failed
-                self._remove_player_data_from_cache('nsig', player_url)
+                # give up if descrambling failed
                 break
             fmt['url'] = update_url_query(fmt['url'], {'n': n_response})
 
@@ -2017,28 +1731,18 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
         Required to tell API what sig/player version is in use.
         """
         sts = traverse_obj(ytcfg, 'STS', expected_type=int)
-        if sts:
-            return sts
-
-        if not player_url:
-            error_msg = 'Cannot extract signature timestamp without player url'
-            if fatal:
-                raise ExtractorError(error_msg)
-            self.report_warning(error_msg)
-            return None
-
-        sts = self._load_player_data_from_cache('sts', player_url)
-        if sts:
-            return sts
-
-        # Attempt to extract from player
-        code = self._load_player(video_id, player_url, fatal=fatal)
-        sts = int_or_none(self._search_regex(
-            r'(?:signatureTimestamp|sts)\s*:\s*(?P<sts>[0-9]{5})', code or '',
-            'JS player signature timestamp', group='sts', fatal=fatal))
-        if sts:
-            self._store_player_data_to_cache('sts', player_url, sts)
-
+        if not sts:
+            # Attempt to extract from player
+            if player_url is None:
+                error_msg = 'Cannot extract signature timestamp without player_url.'
+                if fatal:
+                    raise ExtractorError(error_msg)
+                self.report_warning(error_msg)
+                return
+            code = self._load_player(video_id, player_url, fatal=fatal)
+            sts = int_or_none(self._search_regex(
+                r'(?:signatureTimestamp|sts)\s*:\s*(?P<sts>[0-9]{5})', code or '',
+                'JS player signature timestamp', group='sts', fatal=fatal))
         return sts
 
     def _mark_watched(self, video_id, player_response):
@@ -2050,8 +1754,8 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
 
         # cpn generation algorithm is reverse engineered from base.js.
         # In fact it works even with dummy cpn.
-        CPN_ALPHABET = string.ascii_letters + string.digits + '-_'
-        cpn = ''.join(CPN_ALPHABET[random.randint(0, 256) & 63] for _ in range(16))
+        CPN_ALPHABET = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_'
+        cpn = ''.join(CPN_ALPHABET[random.randint(0, 256) & 63] for _ in range(0, 16))
 
         # more consistent results setting it to right before the end
         qs = parse_qs(playback_url)
@@ -2111,7 +1815,8 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
         mobj = re.match(cls._VALID_URL, url, re.VERBOSE)
         if mobj is None:
             raise ExtractorError('Invalid URL: %s' % url)
-        return mobj.group(2)
+        video_id = mobj.group(2)
+        return video_id
 
     def _extract_chapters_from_json(self, data, video_id, duration):
         chapters_list = try_get(
@@ -2172,89 +1877,9 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
             player_response = self._extract_yt_initial_variable(
                 webpage, self._YT_INITIAL_PLAYER_RESPONSE_RE,
                 video_id, 'initial player response')
-        is_live = traverse_obj(player_response, ('videoDetails', 'isLive'))
-
-        if False and not player_response:
+        if not player_response:
             player_response = self._call_api(
                 'player', {'videoId': video_id}, video_id)
-        if True or not player_response:
-            origin = 'https://www.youtube.com'
-            pb_context = {'html5Preference': 'HTML5_PREF_WANTS'}
-
-            player_url = self._extract_player_url(webpage)
-            ytcfg = self._extract_ytcfg(video_id, webpage or '')
-            sts = self._extract_signature_timestamp(video_id, player_url, ytcfg)
-            if sts:
-                pb_context['signatureTimestamp'] = sts
-
-            client_names = traverse_obj(self._INNERTUBE_CLIENTS, (
-                T(dict.items), lambda _, k_v: not k_v[1].get('REQUIRE_PO_TOKEN'),
-                0))[:1]
-            if 'web' not in client_names:
-                # webpage links won't download: ignore links and playability
-                player_response = filter_dict(
-                    player_response or {},
-                    lambda k, _: k not in ('streamingData', 'playabilityStatus'))
-
-            if is_live and 'ios' not in client_names:
-                client_names.append('ios')
-
-            headers = {
-                'Sec-Fetch-Mode': 'navigate',
-                'Origin': origin,
-                'X-Goog-Visitor-Id': self._extract_visitor_data(ytcfg) or '',
-            }
-            auth = self._generate_sapisidhash_header(origin)
-            if auth is not None:
-                headers['Authorization'] = auth
-                headers['X-Origin'] = origin
-
-            for client in traverse_obj(self._INNERTUBE_CLIENTS, (client_names, T(dict))):
-
-                query = {
-                    'playbackContext': {
-                        'contentPlaybackContext': pb_context,
-                    },
-                    'contentCheckOk': True,
-                    'racyCheckOk': True,
-                    'context': {
-                        'client': merge_dicts(
-                            traverse_obj(client, ('INNERTUBE_CONTEXT', 'client')), {
-                                'hl': 'en',
-                                'timeZone': 'UTC',
-                                'utcOffsetMinutes': 0,
-                            }),
-                    },
-                    'videoId': video_id,
-                }
-
-                api_headers = merge_dicts(headers, traverse_obj(client, {
-                    'X-YouTube-Client-Name': 'INNERTUBE_CONTEXT_CLIENT_NAME',
-                    'X-YouTube-Client-Version': (
-                        'INNERTUBE_CONTEXT', 'client', 'clientVersion'),
-                    'User-Agent': (
-                        'INNERTUBE_CONTEXT', 'client', 'userAgent'),
-                }))
-
-                api_player_response = self._call_api(
-                    'player', query, video_id, fatal=False, headers=api_headers,
-                    note=join_nonempty(
-                        'Downloading', traverse_obj(query, (
-                            'context', 'client', 'clientName')),
-                        'API JSON', delim=' '))
-
-                hls = traverse_obj(
-                    (player_response, api_player_response),
-                    (Ellipsis, 'streamingData', 'hlsManifestUrl', T(url_or_none)))
-                if len(hls) == 2 and not hls[0] and hls[1]:
-                    player_response['streamingData']['hlsManifestUrl'] = hls[1]
-                else:
-                    video_details = merge_dicts(*traverse_obj(
-                        (player_response, api_player_response),
-                        (Ellipsis, 'videoDetails', T(dict))))
-                    player_response.update(filter_dict(
-                        api_player_response or {}, cndn=lambda k, _: k != 'captions'))
-                    player_response['videoDetails'] = video_details
 
         def is_agegated(playability):
             if not isinstance(playability, dict):
@@ -2303,7 +1928,7 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
             headers = {
                 'X-YouTube-Client-Name': '85',
                 'X-YouTube-Client-Version': '2.0',
-                'Origin': 'https://www.youtube.com',
+                'Origin': 'https://www.youtube.com'
             }
 
             video_info = self._call_api('player', query, video_id, fatal=False, headers=headers)
@@ -2332,8 +1957,8 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
             return ''.join([r['text'] for r in runs if isinstance(r.get('text'), compat_str)])
 
         search_meta = (
-            (lambda x: self._html_search_meta(x, webpage, default=None))
-            if webpage else lambda _: None)
+            lambda x: self._html_search_meta(x, webpage, default=None)) \
+            if webpage else lambda x: None
 
         video_details = player_response.get('videoDetails') or {}
         microformat = try_get(
@@ -2397,7 +2022,6 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
         itag_qualities = {}
         q = qualities(['tiny', 'small', 'medium', 'large', 'hd720', 'hd1080', 'hd1440', 'hd2160', 'hd2880', 'highres'])
         CHUNK_SIZE = 10 << 20
-        is_live = video_details.get('isLive')
 
         streaming_data = player_response.get('streamingData') or {}
         streaming_formats = streaming_data.get('formats') or []
@@ -2406,7 +2030,7 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
         def build_fragments(f):
             return LazyList({
                 'url': update_url_query(f['url'], {
-                    'range': '{0}-{1}'.format(range_start, min(range_start + CHUNK_SIZE - 1, f['filesize'])),
+                    'range': '{0}-{1}'.format(range_start, min(range_start + CHUNK_SIZE - 1, f['filesize']))
                 })
             } for range_start in range(0, f['filesize'], CHUNK_SIZE))
 
@@ -2505,7 +2129,7 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
                     'protocol': 'http_dash_segments',
                     'fragments': build_fragments(dct),
                 } if dct['filesize'] else {
-                    'downloader_options': {'http_chunk_size': CHUNK_SIZE},  # No longer useful?
+                    'downloader_options': {'http_chunk_size': CHUNK_SIZE}  # No longer useful?
                 })
 
             formats.append(dct)
@@ -2542,8 +2166,7 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
         hls_manifest_url = streaming_data.get('hlsManifestUrl')
         if hls_manifest_url:
             for f in self._extract_m3u8_formats(
-                    hls_manifest_url, video_id, 'mp4',
-                    entry_protocol='m3u8_native', live=is_live, fatal=False):
+                    hls_manifest_url, video_id, 'mp4', fatal=False):
                 if process_manifest_format(
                         f, 'hls', None, self._search_regex(
                             r'/itag/(\d+)', f['url'], 'itag', default=None)):
@@ -2563,12 +2186,12 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
                         formats.append(f)
 
         playable_formats = [f for f in formats if not f.get('has_drm')]
-        if formats:
-            if not playable_formats:
-                # If there are no formats that definitely don't have DRM, all have DRM
-                self.report_drm(video_id)
-            formats[:] = playable_formats
-        else:
+        if formats and not playable_formats:
+            # If there are no formats that definitely don't have DRM, all have DRM
+            self.report_drm(video_id)
+        formats[:] = playable_formats
+
+        if not formats:
             if streaming_data.get('licenseInfos'):
                 raise ExtractorError(
                     'This video is DRM protected.', expected=True)
@@ -2649,6 +2272,8 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
                 # Strictly de-prioritize damaged formats
                 f['preference'] = -10
 
+        is_live = video_details.get('isLive')
+
         owner_profile_url = self._yt_urljoin(self._extract_author_var(
             webpage, 'url', videodetails=video_details, metadata=microformat))
 
@@ -2682,9 +2307,9 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
             'is_live': is_live,
         }
 
-        pctr = traverse_obj(
-            (player_response, api_player_response),
-            (Ellipsis, 'captions', 'playerCaptionsTracklistRenderer', T(dict)))
+        pctr = try_get(
+            player_response,
+            lambda x: x['captions']['playerCaptionsTracklistRenderer'], dict)
         if pctr:
             def process_language(container, base_url, lang_code, query):
                 lang_subs = []
@@ -2698,35 +2323,31 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
                     })
                 container[lang_code] = lang_subs
 
-            def process_subtitles():
-                subtitles = {}
-                for caption_track in traverse_obj(pctr, (
-                        Ellipsis, 'captionTracks', lambda _, v: (
-                            v.get('baseUrl') and v.get('languageCode')))):
-                    base_url = self._yt_urljoin(caption_track['baseUrl'])
-                    if not base_url:
+            subtitles = {}
+            for caption_track in (pctr.get('captionTracks') or []):
+                base_url = caption_track.get('baseUrl')
+                if not base_url:
+                    continue
+                if caption_track.get('kind') != 'asr':
+                    lang_code = caption_track.get('languageCode')
+                    if not lang_code:
                         continue
-                    lang_code = caption_track['languageCode']
-                    if caption_track.get('kind') != 'asr':
-                        process_language(
-                            subtitles, base_url, lang_code, {})
-                        continue
-                    automatic_captions = {}
                     process_language(
-                        automatic_captions, base_url, lang_code, {})
-                    for translation_language in traverse_obj(pctr, (
-                            Ellipsis, 'translationLanguages', lambda _, v: v.get('languageCode'))):
-                        translation_language_code = translation_language['languageCode']
-                        process_language(
-                            automatic_captions, base_url, translation_language_code,
-                            {'tlang': translation_language_code})
-                    info['automatic_captions'] = automatic_captions
-                info['subtitles'] = subtitles
-
-            process_subtitles()
+                        subtitles, base_url, lang_code, {})
+                    continue
+                automatic_captions = {}
+                for translation_language in (pctr.get('translationLanguages') or []):
+                    translation_language_code = translation_language.get('languageCode')
+                    if not translation_language_code:
+                        continue
+                    process_language(
+                        automatic_captions, base_url, translation_language_code,
+                        {'tlang': translation_language_code})
+                info['automatic_captions'] = automatic_captions
+            info['subtitles'] = subtitles
 
         parsed_url = compat_urllib_parse_urlparse(url)
-        for component in (parsed_url.fragment, parsed_url.query):
+        for component in [parsed_url.fragment, parsed_url.query]:
             query = compat_parse_qs(component)
             for k, v in query.items():
                 for d_k, s_ks in [('start', ('start', 't')), ('end', ('end',))]:
@@ -2956,7 +2577,7 @@ class YoutubeTabIE(YoutubeBaseInfoExtractor):
             'title': 'Super Cooper Shorts - Shorts',
             'uploader': 'Super Cooper Shorts',
             'uploader_id': '@SuperCooperShorts',
-        },
+        }
     }, {
         # Channel that does not have a Shorts tab. Test should just download videos on Home tab instead
         'url': 'https://www.youtube.com/@emergencyawesome/shorts',
@@ -3010,7 +2631,7 @@ class YoutubeTabIE(YoutubeBaseInfoExtractor):
             'description': 'md5:609399d937ea957b0f53cbffb747a14c',
             'uploader': 'ThirstForScience',
             'uploader_id': '@ThirstForScience',
-        },
+        }
     }, {
         'url': 'https://www.youtube.com/c/ChristophLaimer/playlists',
         'only_matching': True,
@@ -3309,7 +2930,7 @@ class YoutubeTabIE(YoutubeBaseInfoExtractor):
             'uploader': '3Blue1Brown',
             'uploader_id': '@3blue1brown',
             'channel_id': 'UCYO_jab_esuFRV4b17AJtAw',
-        },
+        }
     }]
 
     @classmethod
@@ -3334,12 +2955,8 @@ class YoutubeTabIE(YoutubeBaseInfoExtractor):
             expected_type=txt_or_none)
 
     def _grid_entries(self, grid_renderer):
-        for item in traverse_obj(grid_renderer, ('items', Ellipsis, T(dict))):
-            lockup_view_model = traverse_obj(item, ('lockupViewModel', T(dict)))
-            if lockup_view_model:
-                entry = self._extract_lockup_view_model(lockup_view_model)
-                if entry:
-                    yield entry
+        for item in grid_renderer['items']:
+            if not isinstance(item, dict):
                 continue
             renderer = self._extract_grid_item_renderer(item)
             if not isinstance(renderer, dict):
@@ -3423,39 +3040,6 @@ class YoutubeTabIE(YoutubeBaseInfoExtractor):
                 continue
             yield self._extract_video(renderer)
 
-    def _extract_lockup_view_model(self, view_model):
-        content_id = view_model.get('contentId')
-        if not content_id:
-            return
-        content_type = view_model.get('contentType')
-        if content_type not in ('LOCKUP_CONTENT_TYPE_PLAYLIST', 'LOCKUP_CONTENT_TYPE_PODCAST'):
-            self.report_warning(
-                'Unsupported lockup view model content type "{0}"{1}'.format(content_type, bug_reports_message()), only_once=True)
-            return
-        return merge_dicts(self.url_result(
-            update_url_query('https://www.youtube.com/playlist', {'list': content_id}),
-            ie=YoutubeTabIE.ie_key(), video_id=content_id), {
-                'title': traverse_obj(view_model, (
-                    'metadata', 'lockupMetadataViewModel', 'title', 'content', T(compat_str))),
-                'thumbnails': self._extract_thumbnails(view_model, (
-                    'contentImage', 'collectionThumbnailViewModel', 'primaryThumbnail',
-                    'thumbnailViewModel', 'image'), final_key='sources'),
-        })
-
-    def _extract_shorts_lockup_view_model(self, view_model):
-        content_id = traverse_obj(view_model, (
-            'onTap', 'innertubeCommand', 'reelWatchEndpoint', 'videoId',
-            T(lambda v: v if YoutubeIE.suitable(v) else None)))
-        if not content_id:
-            return
-        return merge_dicts(self.url_result(
-            content_id, ie=YoutubeIE.ie_key(), video_id=content_id), {
-                'title': traverse_obj(view_model, (
-                    'overlayMetadata', 'primaryText', 'content', T(compat_str))),
-                'thumbnails': self._extract_thumbnails(
-                    view_model, 'thumbnail', final_key='sources'),
-        })
-
     def _video_entry(self, video_renderer):
         video_id = video_renderer.get('videoId')
         if video_id:
@@ -3502,9 +3086,10 @@ class YoutubeTabIE(YoutubeBaseInfoExtractor):
                 yield entry
 
     def _rich_grid_entries(self, contents):
-        for content in traverse_obj(
-                contents, (Ellipsis, 'richItemRenderer', 'content'),
-                expected_type=dict):
+        for content in contents:
+            content = traverse_obj(
+                content, ('richItemRenderer', 'content'),
+                expected_type=dict) or {}
             video_renderer = traverse_obj(
                 content, 'videoRenderer', 'reelItemRenderer',
                 expected_type=dict)
@@ -3512,12 +3097,6 @@ class YoutubeTabIE(YoutubeBaseInfoExtractor):
                 entry = self._video_entry(video_renderer)
                 if entry:
                     yield entry
-            # shorts item
-            shorts_lockup_view_model = content.get('shortsLockupViewModel')
-            if shorts_lockup_view_model:
-                entry = self._extract_shorts_lockup_view_model(shorts_lockup_view_model)
-                if entry:
-                    yield entry
             # playlist
             renderer = traverse_obj(
                 content, 'playlistRenderer', expected_type=dict) or {}
@@ -3556,15 +3135,23 @@ class YoutubeTabIE(YoutubeBaseInfoExtractor):
         next_continuation = cls._extract_next_continuation_data(renderer)
         if next_continuation:
             return next_continuation
-        for command in traverse_obj(renderer, (
-                ('contents', 'items', 'rows'), Ellipsis, 'continuationItemRenderer',
-                ('continuationEndpoint', ('button', 'buttonRenderer', 'command')),
-                (('commandExecutorCommand', 'commands', Ellipsis), None), T(dict))):
-            continuation = traverse_obj(command, ('continuationCommand', 'token', T(compat_str)))
+        contents = []
+        for key in ('contents', 'items'):
+            contents.extend(try_get(renderer, lambda x: x[key], list) or [])
+        for content in contents:
+            if not isinstance(content, dict):
+                continue
+            continuation_ep = try_get(
+                content, lambda x: x['continuationItemRenderer']['continuationEndpoint'],
+                dict)
+            if not continuation_ep:
+                continue
+            continuation = try_get(
+                continuation_ep, lambda x: x['continuationCommand']['token'], compat_str)
             if not continuation:
                 continue
-            ctp = command.get('clickTrackingParams')
-            return cls._build_continuation_query(continuation, ctp)
+            ctp = continuation_ep.get('clickTrackingParams')
+            return YoutubeTabIE._build_continuation_query(continuation, ctp)
 
     def _entries(self, tab, item_id, webpage):
         tab_content = try_get(tab, lambda x: x['content'], dict)
@@ -3613,13 +3200,6 @@ class YoutubeTabIE(YoutubeBaseInfoExtractor):
                         entry = self._video_entry(renderer)
                         if entry:
                             yield entry
-                    renderer = isr_content.get('richGridRenderer')
-                    if renderer:
-                        for from_ in self._rich_grid_entries(
-                                traverse_obj(renderer, ('contents', Ellipsis, T(dict)))):
-                            yield from_
-                        continuation = self._extract_continuation(renderer)
-                        continue
 
                 if not continuation:
                     continuation = self._extract_continuation(is_renderer)
@@ -3629,9 +3209,8 @@ class YoutubeTabIE(YoutubeBaseInfoExtractor):
             rich_grid_renderer = tab_content.get('richGridRenderer')
             if not rich_grid_renderer:
                 return
-            for from_ in self._rich_grid_entries(
-                    traverse_obj(rich_grid_renderer, ('contents', Ellipsis, T(dict)))):
-                yield from_
+            for entry in self._rich_grid_entries(rich_grid_renderer.get('contents') or []):
+                yield entry
 
             continuation = self._extract_continuation(rich_grid_renderer)
 
@@ -3649,7 +3228,7 @@ class YoutubeTabIE(YoutubeBaseInfoExtractor):
             'client': {
                 'clientName': 'WEB',
                 'clientVersion': client_version,
-            },
+            }
         }
         visitor_data = try_get(context, lambda x: x['client']['visitorData'], compat_str)
 
@@ -3665,10 +3244,10 @@ class YoutubeTabIE(YoutubeBaseInfoExtractor):
             if not continuation:
                 break
             if visitor_data:
-                headers['X-Goog-Visitor-Id'] = visitor_data
+                headers['x-goog-visitor-id'] = visitor_data
             data['continuation'] = continuation['continuation']
             data['clickTracking'] = {
-                'clickTrackingParams': continuation['itct'],
+                'clickTrackingParams': continuation['itct']
             }
             count = 0
             retries = 3
@@ -3677,12 +3256,8 @@ class YoutubeTabIE(YoutubeBaseInfoExtractor):
                     # Downloading page may result in intermittent 5xx HTTP error
                     # that is usually worked around with a retry
                     response = self._download_json(
-                        'https://www.youtube.com/youtubei/v1/browse',
+                        'https://www.youtube.com/youtubei/v1/browse?key=AIzaSyAO_FJ2SlqU8Q4STEHLGCilw_Y9_11qcW8',
                         None, 'Downloading page %d%s' % (page_num, ' (retry #%d)' % count if count else ''),
-                        query={
-                            # 'key': 'AIzaSyAO_FJ2SlqU8Q4STEHLGCilw_Y9_11qcW8',
-                            'prettyPrint': 'false',
-                        },
                         headers=headers, data=json.dumps(data).encode('utf8'))
                     break
                 except ExtractorError as e:
@@ -3851,23 +3426,10 @@ class YoutubeTabIE(YoutubeBaseInfoExtractor):
     def _real_extract(self, url):
         item_id = self._match_id(url)
         url = update_url(url, netloc='www.youtube.com')
-        qs = parse_qs(url)
-
-        def qs_get(key, default=None):
-            return qs.get(key, [default])[-1]
-
-        # Go around for /feeds/videos.xml?playlist_id={pl_id}
-        if item_id == 'feeds' and '/feeds/videos.xml?' in url:
-            playlist_id = qs_get('playlist_id')
-            if playlist_id:
-                return self.url_result(
-                    update_url_query('https://www.youtube.com/playlist', {
-                        'list': playlist_id,
-                    }), ie=self.ie_key(), video_id=playlist_id)
-
         # Handle both video/playlist URLs
-        video_id = qs_get('v')
-        playlist_id = qs_get('list')
+        qs = parse_qs(url)
+        video_id = qs.get('v', [None])[0]
+        playlist_id = qs.get('list', [None])[0]
         if video_id and playlist_id:
             if self._downloader.params.get('noplaylist'):
                 self.to_screen('Downloading just video %s because of --no-playlist' % video_id)
@@ -3944,7 +3506,7 @@ class YoutubePlaylistIE(InfoExtractor):
             'uploader': 'milan',
             'uploader_id': '@milan5503',
             'channel_id': 'UCEI1-PVPcYXjB73Hfelbmaw',
-        },
+        }
     }, {
         'url': 'http://www.youtube.com/embed/_xDOZElKyNU?list=PLsyOSbh5bs16vubvKePAQ1x3PhKavfBIl',
         'playlist_mincount': 455,
@@ -3954,7 +3516,7 @@ class YoutubePlaylistIE(InfoExtractor):
             'uploader': 'LBK',
             'uploader_id': '@music_king',
             'channel_id': 'UC21nz3_MesPLqtDqwdvnoxA',
-        },
+        }
     }, {
         'url': 'TLGGrESM50VT6acwMjAyMjAxNw',
         'only_matching': True,
@@ -4065,7 +3627,7 @@ class YoutubeSearchIE(SearchInfoExtractor, YoutubeBaseInfoExtractor):
         'info_dict': {
             'id': 'youtube-dl test video',
             'title': 'youtube-dl test video',
-        },
+        }
     }]
 
     def _get_n_results(self, query, n):
@@ -4085,7 +3647,7 @@ class YoutubeSearchDateIE(YoutubeSearchIE):
         'info_dict': {
             'id': 'youtube-dl test video',
             'title': 'youtube-dl test video',
-        },
+        }
     }]
 
 
@@ -4100,7 +3662,7 @@ class YoutubeSearchURLIE(YoutubeBaseInfoExtractor):
             'id': 'youtube-dl test video',
             'title': 'youtube-dl test video',
         },
-        'params': {'playlistend': 5},
+        'params': {'playlistend': 5}
     }, {
         'url': 'https://www.youtube.com/results?q=test&sp=EgQIBBgB',
         'only_matching': True,
@@ -4116,7 +3678,6 @@ class YoutubeSearchURLIE(YoutubeBaseInfoExtractor):
 class YoutubeFeedsInfoExtractor(YoutubeTabIE):
     """
     Base class for feed extractors
-
     Subclasses must define the _FEED_NAME property.
     """
     _LOGIN_REQUIRED = True
diff --git a/youtube_dl/jsinterp.py b/youtube_dl/jsinterp.py
index 7630e2099..949f77775 100644
--- a/youtube_dl/jsinterp.py
+++ b/youtube_dl/jsinterp.py
@@ -1,23 +1,17 @@
-# coding: utf-8
 from __future__ import unicode_literals
 
-import calendar
 import itertools
 import json
 import operator
 import re
-import time
 
-from functools import update_wrapper, wraps
+from functools import update_wrapper
 
 from .utils import (
     error_to_compat_str,
     ExtractorError,
-    float_or_none,
-    int_or_none,
     js_to_json,
     remove_quotes,
-    str_or_none,
     unified_timestamp,
     variadic,
     write_string,
@@ -26,13 +20,9 @@ from .compat import (
     compat_basestring,
     compat_chr,
     compat_collections_chain_map as ChainMap,
-    compat_contextlib_suppress,
     compat_filter as filter,
-    compat_int,
-    compat_integer_types,
     compat_itertools_zip_longest as zip_longest,
     compat_map as map,
-    compat_numeric_types,
     compat_str,
 )
 
@@ -72,144 +62,55 @@ _NaN = float('nan')
 _Infinity = float('inf')
 
 
-class JS_Undefined(object):
-    pass
+def _js_bit_op(op):
 
-
-def _js_bit_op(op, is_shift=False):
-
-    def zeroise(x, is_shift_arg=False):
-        if isinstance(x, compat_integer_types):
-            return (x % 32) if is_shift_arg else (x & 0xffffffff)
-        try:
-            x = float(x)
-            if is_shift_arg:
-                x = int(x % 32)
-            elif x < 0:
-                x = -compat_int(-x % 0xffffffff)
-            else:
-                x = compat_int(x % 0xffffffff)
-        except (ValueError, TypeError):
-            # also here for int(NaN), including float('inf') % 32
-            x = 0
-        return x
+    def zeroise(x):
+        return 0 if x in (None, JS_Undefined, _NaN, _Infinity) else x
 
     @wraps_op(op)
     def wrapped(a, b):
-        return op(zeroise(a), zeroise(b, is_shift)) & 0xffffffff
+        return op(zeroise(a), zeroise(b)) & 0xffffffff
 
     return wrapped
 
 
-def _js_arith_op(op, div=False):
+def _js_arith_op(op):
 
     @wraps_op(op)
     def wrapped(a, b):
         if JS_Undefined in (a, b):
             return _NaN
-        # null, "" --> 0
-        a, b = (float_or_none(
-            (x.strip() if isinstance(x, compat_basestring) else x) or 0,
-            default=_NaN) for x in (a, b))
-        if _NaN in (a, b):
-            return _NaN
-        try:
-            return op(a, b)
-        except ZeroDivisionError:
-            return _NaN if not (div and (a or b)) else _Infinity
+        return op(a or 0, b or 0)
 
     return wrapped
 
 
-_js_arith_add = _js_arith_op(operator.add)
+def _js_div(a, b):
+    if JS_Undefined in (a, b) or not (a or b):
+        return _NaN
+    return operator.truediv(a or 0, b) if b else _Infinity
 
 
-def _js_add(a, b):
-    if not (isinstance(a, compat_basestring) or isinstance(b, compat_basestring)):
-        return _js_arith_add(a, b)
-    if not isinstance(a, compat_basestring):
-        a = _js_toString(a)
-    elif not isinstance(b, compat_basestring):
-        b = _js_toString(b)
-    return operator.concat(a, b)
-
-
-_js_mod = _js_arith_op(operator.mod)
-__js_exp = _js_arith_op(operator.pow)
+def _js_mod(a, b):
+    if JS_Undefined in (a, b) or not b:
+        return _NaN
+    return (a or 0) % b
 
 
 def _js_exp(a, b):
     if not b:
         return 1  # even 0 ** 0 !!
-    return __js_exp(a, b)
+    elif JS_Undefined in (a, b):
+        return _NaN
+    return (a or 0) ** b
 
 
-def _js_to_primitive(v):
-    return (
-        ','.join(map(_js_toString, v)) if isinstance(v, list)
-        else '[object Object]' if isinstance(v, dict)
-        else compat_str(v) if not isinstance(v, (
-            compat_numeric_types, compat_basestring))
-        else v
-    )
-
-
-# more exact: yt-dlp/yt-dlp#12110
-def _js_toString(v):
-    return (
-        'undefined' if v is JS_Undefined
-        else 'Infinity' if v == _Infinity
-        else 'NaN' if v is _NaN
-        else 'null' if v is None
-        # bool <= int: do this first
-        else ('false', 'true')[v] if isinstance(v, bool)
-        else re.sub(r'(?<=\d)\.?0*$', '', '{0:.7f}'.format(v)) if isinstance(v, compat_numeric_types)
-        else _js_to_primitive(v))
-
-
-_nullish = frozenset((None, JS_Undefined))
-
-
-def _js_eq(a, b):
-    # NaN != any
-    if _NaN in (a, b):
-        return False
-    # Object is Object
-    if isinstance(a, type(b)) and isinstance(b, (dict, list)):
-        return operator.is_(a, b)
-    # general case
-    if a == b:
-        return True
-    # null == undefined
-    a_b = set((a, b))
-    if a_b & _nullish:
-        return a_b <= _nullish
-    a, b = _js_to_primitive(a), _js_to_primitive(b)
-    if not isinstance(a, compat_basestring):
-        a, b = b, a
-    # Number to String: convert the string to a number
-    # Conversion failure results in ... false
-    if isinstance(a, compat_basestring):
-        return float_or_none(a) == b
-    return a == b
-
-
-def _js_neq(a, b):
-    return not _js_eq(a, b)
-
-
-def _js_id_op(op):
+def _js_eq_op(op):
 
     @wraps_op(op)
     def wrapped(a, b):
-        if _NaN in (a, b):
-            return op(_NaN, None)
-        if not isinstance(a, (compat_basestring, compat_numeric_types)):
-            a, b = b, a
-        # strings are === if ==
-        # why 'a' is not 'a': https://stackoverflow.com/a/1504848
-        if isinstance(a, (compat_basestring, compat_numeric_types)):
-            return a == b if op(0, 0) else a != b
+        if set((a, b)) <= set((None, JS_Undefined)):
+            return op(a, a)
         return op(a, b)
 
     return wrapped
@@ -237,52 +138,31 @@ def _js_ternary(cndn, if_true=True, if_false=False):
     return if_true
 
 
-def _js_unary_op(op):
-
-    @wraps_op(op)
-    def wrapped(a, _):
-        return op(a)
-
-    return wrapped
-
-
-# https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/typeof
-def _js_typeof(expr):
-    with compat_contextlib_suppress(TypeError, KeyError):
-        return {
-            JS_Undefined: 'undefined',
-            _NaN: 'number',
-            _Infinity: 'number',
-            True: 'boolean',
-            False: 'boolean',
-            None: 'object',
-        }[expr]
-    for t, n in (
-        (compat_basestring, 'string'),
-        (compat_numeric_types, 'number'),
-    ):
-        if isinstance(expr, t):
-            return n
-    if callable(expr):
-        return 'function'
-    # TODO: Symbol, BigInt
-    return 'object'
-
-
 # (op, definition) in order of binding priority, tightest first
 # avoid dict to maintain order
 # definition None => Defined in JSInterpreter._operator
 _OPERATORS = (
-    ('>>', _js_bit_op(operator.rshift, True)),
-    ('<<', _js_bit_op(operator.lshift, True)),
-    ('+', _js_add),
+    ('>>', _js_bit_op(operator.rshift)),
+    ('<<', _js_bit_op(operator.lshift)),
+    ('+', _js_arith_op(operator.add)),
     ('-', _js_arith_op(operator.sub)),
     ('*', _js_arith_op(operator.mul)),
     ('%', _js_mod),
-    ('/', _js_arith_op(operator.truediv, div=True)),
+    ('/', _js_div),
     ('**', _js_exp),
 )
 
+_COMP_OPERATORS = (
+    ('===', operator.is_),
+    ('!==', operator.is_not),
+    ('==', _js_eq_op(operator.eq)),
+    ('!=', _js_eq_op(operator.ne)),
+    ('<=', _js_comp_op(operator.le)),
+    ('>=', _js_comp_op(operator.ge)),
+    ('<', _js_comp_op(operator.lt)),
+    ('>', _js_comp_op(operator.gt)),
+)
+
 _LOG_OPERATORS = (
     ('|', _js_bit_op(operator.or_)),
     ('^', _js_bit_op(operator.xor)),
@@ -296,30 +176,15 @@ _SC_OPERATORS = (
     ('&&', None),
 )
 
-_UNARY_OPERATORS_X = (
-    ('void', _js_unary_op(lambda _: JS_Undefined)),
-    ('typeof', _js_unary_op(_js_typeof)),
-    # avoid functools.partial here since Py2 update_wrapper(partial) -> no __module__
-    ('!', _js_unary_op(lambda x: _js_ternary(x, if_true=False, if_false=True))),
-)
-
-_COMP_OPERATORS = (
-    ('===', _js_id_op(operator.is_)),
-    ('!==', _js_id_op(operator.is_not)),
-    ('==', _js_eq),
-    ('!=', _js_neq),
-    ('<=', _js_comp_op(operator.le)),
-    ('>=', _js_comp_op(operator.ge)),
-    ('<', _js_comp_op(operator.lt)),
-    ('>', _js_comp_op(operator.gt)),
-)
-
-_OPERATOR_RE = '|'.join(map(lambda x: re.escape(x[0]), _OPERATORS + _LOG_OPERATORS + _SC_OPERATORS))
+_OPERATOR_RE = '|'.join(map(lambda x: re.escape(x[0]), _OPERATORS + _LOG_OPERATORS))
 
 _NAME_RE = r'[a-zA-Z_$][\w$]*'
 _MATCHING_PARENS = dict(zip(*zip('()', '{}', '[]')))
 _QUOTES = '\'"/'
-_NESTED_BRACKETS = r'[^[\]]+(?:\[[^[\]]+(?:\[[^\]]+\])?\])?'
+
+
+class JS_Undefined(object):
+    pass
 
 
 class JS_Break(ExtractorError):
@@ -356,7 +221,7 @@ class LocalNameSpace(ChainMap):
         raise NotImplementedError('Deleting is not supported')
 
     def __repr__(self):
-        return 'LocalNameSpace({0!r})'.format(self.maps)
+        return 'LocalNameSpace%s' % (self.maps, )
 
 
 class Debugger(object):
@@ -377,10 +242,6 @@ class Debugger(object):
 
     @classmethod
     def wrap_interpreter(cls, f):
-        if not cls.ENABLED:
-            return f
-
-        @wraps(f)
         def interpret_statement(self, stmt, local_vars, allow_recursion, *args, **kwargs):
             if cls.ENABLED and stmt.strip():
                 cls.write(stmt, level=allow_recursion)
@@ -394,7 +255,7 @@ class Debugger(object):
                 raise
             if cls.ENABLED and stmt.strip():
                 if should_ret or repr(ret) != stmt:
-                    cls.write(['->', '=>'][bool(should_ret)], repr(ret), '<-|', stmt, level=allow_recursion)
+                    cls.write(['->', '=>'][should_ret], repr(ret), '<-|', stmt, level=allow_recursion)
             return ret, should_ret
         return interpret_statement
 
@@ -415,28 +276,14 @@ class JSInterpreter(object):
     class Exception(ExtractorError):
         def __init__(self, msg, *args, **kwargs):
             expr = kwargs.pop('expr', None)
-            msg = str_or_none(msg, default='"None"')
             if expr is not None:
                 msg = '{0} in: {1!r:.100}'.format(msg.rstrip(), expr)
             super(JSInterpreter.Exception, self).__init__(msg, *args, **kwargs)
 
-    class JS_Object(object):
-        def __getitem__(self, key):
-            if hasattr(self, key):
-                return getattr(self, key)
-            raise KeyError(key)
-
-        def dump(self):
-            """Serialise the instance"""
-            raise NotImplementedError
-
-    class JS_RegExp(JS_Object):
+    class JS_RegExp(object):
         RE_FLAGS = {
             # special knowledge: Python's re flags are bitmask values, current max 128
             # invent new bitmask values well above that for literal parsing
-            # JS 'u' flag is effectively always set (surrogate pairs aren't seen),
-            # but \u{...} and \p{...} escapes aren't handled); no additional JS 'v'
-            # features are supported
             # TODO: execute matches with these flags (remaining: d, y)
             'd': 1024,  # Generate indices for substring matches
             'g': 2048,  # Global search
@@ -444,31 +291,21 @@ class JSInterpreter(object):
             'm': re.M,  # Multi-line search
             's': re.S,  # Allows . to match newline characters
             'u': re.U,  # Treat a pattern as a sequence of unicode code points
-            'v': re.U,  # Like 'u' with extended character class and \p{} syntax
             'y': 4096,  # Perform a "sticky" search that matches starting at the current position in the target string
         }
 
         def __init__(self, pattern_txt, flags=0):
             if isinstance(flags, compat_str):
                 flags, _ = self.regex_flags(flags)
+            # First, avoid https://github.com/python/cpython/issues/74534
             self.__self = None
-            pattern_txt = str_or_none(pattern_txt) or '(?:)'
-            # escape unintended embedded flags
-            pattern_txt = re.sub(
-                r'(\(\?)([aiLmsux]*)(-[imsx]+:|(?<!\?)\))',
-                lambda m: ''.join(
-                    (re.escape(m.group(1)), m.group(2), re.escape(m.group(3)))
-                    if m.group(3) == ')'
-                    else ('(?:', m.group(2), m.group(3))),
-                pattern_txt)
-            # Avoid https://github.com/python/cpython/issues/74534
-            self.source = pattern_txt.replace('[[', r'[\[')
+            self.__pattern_txt = pattern_txt.replace('[[', r'[\[')
             self.__flags = flags
 
         def __instantiate(self):
             if self.__self:
                 return
-            self.__self = re.compile(self.source, self.__flags)
+            self.__self = re.compile(self.__pattern_txt, self.__flags)
             # Thx: https://stackoverflow.com/questions/44773522/setattr-on-python2-sre-sre-pattern
             for name in dir(self.__self):
                 # Only these? Obviously __class__, __init__.
@@ -476,15 +313,16 @@ class JSInterpreter(object):
                 # that can't be setattr'd but also can't need to be copied.
                 if name in ('__class__', '__init__', '__weakref__'):
                     continue
-                if name == 'flags':
-                    setattr(self, name, getattr(self.__self, name, self.__flags))
-                else:
-                    setattr(self, name, getattr(self.__self, name))
+                setattr(self, name, getattr(self.__self, name))
 
         def __getattr__(self, name):
             self.__instantiate()
-            if name == 'pattern':
-                self.pattern = self.source
+            # make Py 2.6 conform to its lying documentation
+            if name == 'flags':
+                self.flags = self.__flags
+                return self.flags
+            elif name == 'pattern':
+                self.pattern = self.__pattern_txt
                 return self.pattern
             elif hasattr(self.__self, name):
                 v = getattr(self.__self, name)
@@ -492,26 +330,6 @@ class JSInterpreter(object):
                 return v
             elif name in ('groupindex', 'groups'):
                 return 0 if name == 'groupindex' else {}
-            else:
-                flag_attrs = (  # order by 2nd elt
-                    ('hasIndices', 'd'),
-                    ('global', 'g'),
-                    ('ignoreCase', 'i'),
-                    ('multiline', 'm'),
-                    ('dotAll', 's'),
-                    ('unicode', 'u'),
-                    ('unicodeSets', 'v'),
-                    ('sticky', 'y'),
-                )
-                for k, c in flag_attrs:
-                    if name == k:
-                        return bool(self.RE_FLAGS[c] & self.__flags)
-                else:
-                    if name == 'flags':
-                        return ''.join(
-                            (c if self.RE_FLAGS[c] & self.__flags else '')
-                            for _, c in flag_attrs)
-
             raise AttributeError('{0} has no attribute named {1}'.format(self, name))
 
         @classmethod
@@ -525,91 +343,10 @@ class JSInterpreter(object):
                 flags |= cls.RE_FLAGS[ch]
             return flags, expr[idx + 1:]
 
-        def dump(self):
-            return '(/{0}/{1})'.format(
-                re.sub(r'(?<!\\)/', r'\/', self.source),
-                self.flags)
-
-        @staticmethod
-        def escape(string_):
-            return re.escape(string_)
-
-    class JS_Date(JS_Object):
-        _t = None
-
-        @staticmethod
-        def __ymd_etc(*args, **kw_is_utc):
-            # args: year, monthIndex, day, hours, minutes, seconds, milliseconds
-            is_utc = kw_is_utc.get('is_utc', False)
-
-            args = list(args[:7])
-            args += [0] * (9 - len(args))
-            args[1] += 1  # month 0..11 -> 1..12
-            ms = args[6]
-            for i in range(6, 9):
-                args[i] = -1  # don't know
-            if is_utc:
-                args[-1] = 1
-            # TODO: [MDN] When a segment overflows or underflows its expected
-            # range, it usually "carries over to" or "borrows from" the higher segment.
-            try:
-                mktime = calendar.timegm if is_utc else time.mktime
-                return mktime(time.struct_time(args)) * 1000 + ms
-            except (OverflowError, ValueError):
-                return None
-
-        @classmethod
-        def UTC(cls, *args):
-            t = cls.__ymd_etc(*args, is_utc=True)
-            return _NaN if t is None else t
-
-        @staticmethod
-        def parse(date_str, **kw_is_raw):
-            is_raw = kw_is_raw.get('is_raw', False)
-
-            t = unified_timestamp(str_or_none(date_str), False)
-            return int(t * 1000) if t is not None else t if is_raw else _NaN
-
-        @staticmethod
-        def now(**kw_is_raw):
-            is_raw = kw_is_raw.get('is_raw', False)
-
-            t = time.time()
-            return int(t * 1000) if t is not None else t if is_raw else _NaN
-
-        def __init__(self, *args):
-            if not args:
-                args = [self.now(is_raw=True)]
-            if len(args) == 1:
-                if isinstance(args[0], JSInterpreter.JS_Date):
-                    self._t = int_or_none(args[0].valueOf(), default=None)
-                else:
-                    arg_type = _js_typeof(args[0])
-                    if arg_type == 'string':
-                        self._t = self.parse(args[0], is_raw=True)
-                    elif arg_type == 'number':
-                        self._t = int(args[0])
-            else:
-                self._t = self.__ymd_etc(*args)
-
-        def toString(self):
-            try:
-                return time.strftime('%a %b %0d %Y %H:%M:%S %Z%z', self._t).rstrip()
-            except TypeError:
-                return "Invalid Date"
-
-        def valueOf(self):
-            return _NaN if self._t is None else self._t
-
-        def dump(self):
-            return '(new Date({0}))'.format(self.toString())
-
     @classmethod
     def __op_chars(cls):
         op_chars = set(';,[')
         for op in cls._all_operators():
-            if op[0].isalpha():
-                continue
             op_chars.update(op[0])
         return op_chars
 
@@ -632,18 +369,9 @@ class JSInterpreter(object):
         skipping = 0
         if skip_delims:
             skip_delims = variadic(skip_delims)
-        skip_txt = None
         for idx, char in enumerate(expr):
-            if skip_txt and idx <= skip_txt[1]:
-                continue
             paren_delta = 0
             if not in_quote:
-                if char == '/' and expr[idx:idx + 2] == '/*':
-                    # skip a comment
-                    skip_txt = expr[idx:].find('*/', 2)
-                    skip_txt = [idx, idx + skip_txt + 1] if skip_txt >= 2 else None
-                    if skip_txt:
-                        continue
                 if char in _MATCHING_PARENS:
                     counters[_MATCHING_PARENS[char]] += 1
                     paren_delta = 1
@@ -676,19 +404,12 @@ class JSInterpreter(object):
             if pos < delim_len:
                 pos += 1
                 continue
-            if skip_txt and skip_txt[0] >= start and skip_txt[1] <= idx - delim_len:
-                yield expr[start:skip_txt[0]] + expr[skip_txt[1] + 1: idx - delim_len]
-            else:
-                yield expr[start: idx - delim_len]
-            skip_txt = None
+            yield expr[start: idx - delim_len]
             start, pos = idx + 1, 0
             splits += 1
             if max_split and splits >= max_split:
                 break
-        if skip_txt and skip_txt[0] >= start:
-            yield expr[start:skip_txt[0]] + expr[skip_txt[1] + 1:]
-        else:
-            yield expr[start:]
+        yield expr[start:]
 
     @classmethod
     def _separate_at_paren(cls, expr, delim=None):
@@ -704,71 +425,9 @@ class JSInterpreter(object):
         if not _cached:
             _cached.extend(itertools.chain(
                 # Ref: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Operator_Precedence
-                _SC_OPERATORS, _LOG_OPERATORS, _COMP_OPERATORS, _OPERATORS, _UNARY_OPERATORS_X))
+                _SC_OPERATORS, _LOG_OPERATORS, _COMP_OPERATORS, _OPERATORS))
         return _cached
 
-    def _separate_at_op(self, expr, max_split=None):
-
-        for op, _ in self._all_operators():
-            # hackety: </> have higher priority than <</>>, but don't confuse them
-            skip_delim = (op + op) if op in '<>*?' else None
-            if op == '?':
-                skip_delim = (skip_delim, '?.')
-            separated = list(self._separate(expr, op, skip_delims=skip_delim))
-            if len(separated) < 2:
-                continue
-
-            right_expr = separated.pop()
-            # handle operators that are both unary and binary, minimal BODMAS
-            if op in ('+', '-'):
-                # simplify/adjust consecutive instances of these operators
-                undone = 0
-                separated = [s.strip() for s in separated]
-                while len(separated) > 1 and not separated[-1]:
-                    undone += 1
-                    separated.pop()
-                if op == '-' and undone % 2 != 0:
-                    right_expr = op + right_expr
-                elif op == '+':
-                    while len(separated) > 1 and set(separated[-1]) <= self.OP_CHARS:
-                        right_expr = separated.pop() + right_expr
-                    if separated[-1][-1:] in self.OP_CHARS:
-                        right_expr = separated.pop() + right_expr
-                # hanging op at end of left => unary + (strip) or - (push right)
-                separated.append(right_expr)
-                dm_ops = ('*', '%', '/', '**')
-                dm_chars = set(''.join(dm_ops))
-
-                def yield_terms(s):
-                    skip = False
-                    for i, term in enumerate(s[:-1]):
-                        if skip:
-                            skip = False
-                            continue
-                        if not (dm_chars & set(term)):
-                            yield term
-                            continue
-                        for dm_op in dm_ops:
-                            bodmas = list(self._separate(term, dm_op, skip_delims=skip_delim))
-                            if len(bodmas) > 1 and not bodmas[-1].strip():
-                                bodmas[-1] = (op if op == '-' else '') + s[i + 1]
-                                yield dm_op.join(bodmas)
-                                skip = True
-                                break
-                        else:
-                            if term:
-                                yield term
-
-                    if not skip and s[-1]:
-                        yield s[-1]
-
-                separated = list(yield_terms(separated))
-                right_expr = separated.pop() if len(separated) > 1 else None
-                expr = op.join(separated)
-            if right_expr is None:
-                continue
-            return op, separated, right_expr
-
     def _operator(self, op, left_val, right_expr, expr, local_vars, allow_recursion):
         if op in ('||', '&&'):
             if (op == '&&') ^ _js_ternary(left_val):
@@ -779,7 +438,7 @@ class JSInterpreter(object):
         elif op == '?':
             right_expr = _js_ternary(left_val, *self._separate(right_expr, ':', 1))
 
-        right_val = self.interpret_expression(right_expr, local_vars, allow_recursion) if right_expr else left_val
+        right_val = self.interpret_expression(right_expr, local_vars, allow_recursion)
         opfunc = op and next((v for k, v in self._all_operators() if k == op), None)
         if not opfunc:
             return right_val
@@ -790,21 +449,17 @@ class JSInterpreter(object):
         except Exception as e:
             raise self.Exception('Failed to evaluate {left_val!r:.50} {op} {right_val!r:.50}'.format(**locals()), expr, cause=e)
 
-    def _index(self, obj, idx, allow_undefined=None):
-        if idx == 'length' and isinstance(obj, list):
+    def _index(self, obj, idx, allow_undefined=False):
+        if idx == 'length':
             return len(obj)
         try:
-            return obj[int(idx)] if isinstance(obj, list) else obj[compat_str(idx)]
-        except (TypeError, KeyError, IndexError, ValueError) as e:
-            # allow_undefined is None gives correct behaviour
-            if allow_undefined or (
-                    allow_undefined is None and not isinstance(e, TypeError)):
+            return obj[int(idx)] if isinstance(obj, list) else obj[idx]
+        except Exception as e:
+            if allow_undefined:
                 return JS_Undefined
             raise self.Exception('Cannot get index {idx!r:.100}'.format(**locals()), expr=repr(obj), cause=e)
 
     def _dump(self, obj, namespace):
-        if obj is JS_Undefined:
-            return 'undefined'
         try:
             return json.dumps(obj)
         except TypeError:
@@ -812,7 +467,7 @@ class JSInterpreter(object):
 
     # used below
     _VAR_RET_THROW_RE = re.compile(r'''(?x)
-        (?:(?P<var>var|const|let)\s+|(?P<ret>return)(?:\s+|(?=["'])|$)|(?P<throw>throw)\s+)
+        (?P<var>(?:var|const|let)\s)|return(?:\s+|(?=["'])|$)|(?P<throw>throw\s+)
         ''')
     _COMPOUND_RE = re.compile(r'''(?x)
         (?P<try>try)\s*\{|
@@ -824,10 +479,6 @@ class JSInterpreter(object):
     _FINALLY_RE = re.compile(r'finally\s*\{')
     _SWITCH_RE = re.compile(r'switch\s*\(')
 
-    def _eval_operator(self, op, left_expr, right_expr, expr, local_vars, allow_recursion):
-        left_val = self.interpret_expression(left_expr, local_vars, allow_recursion)
-        return self._operator(op, left_val, right_expr, expr, local_vars, allow_recursion)
-
     @Debugger.wrap_interpreter
     def interpret_statement(self, stmt, local_vars, allow_recursion=100):
         if allow_recursion < 0:
@@ -850,7 +501,7 @@ class JSInterpreter(object):
             expr = stmt[len(m.group(0)):].strip()
             if m.group('throw'):
                 raise JS_Throw(self.interpret_expression(expr, local_vars, allow_recursion))
-            should_return = 'return' if m.group('ret') else False
+            should_return = not m.group('var')
         if not expr:
             return None, should_return
 
@@ -867,7 +518,7 @@ class JSInterpreter(object):
 
         new_kw, _, obj = expr.partition('new ')
         if not new_kw:
-            for klass, konstr in (('Date', lambda *x: self.JS_Date(*x).valueOf()),
+            for klass, konstr in (('Date', lambda x: int(unified_timestamp(x, False) * 1000)),
                                   ('RegExp', self.JS_RegExp),
                                   ('Error', self.Exception)):
                 if not obj.startswith(klass + '('):
@@ -882,19 +533,9 @@ class JSInterpreter(object):
             else:
                 raise self.Exception('Unsupported object {obj:.100}'.format(**locals()), expr=expr)
 
-        # apply unary operators (see new above)
-        for op, _ in _UNARY_OPERATORS_X:
-            if not expr.startswith(op):
-                continue
-            operand = expr[len(op):]
-            if not operand or (op.isalpha() and operand[0] != ' '):
-                continue
-            separated = self._separate_at_op(operand, max_split=1)
-            if separated:
-                next_op, separated, right_expr = separated
-                separated.append(right_expr)
-                operand = next_op.join(separated)
-            return self._eval_operator(op, operand, '', expr, local_vars, allow_recursion), should_return
+        if expr.startswith('void '):
+            left = self.interpret_expression(expr[5:], local_vars, allow_recursion)
+            return None, should_return
 
         if expr.startswith('{'):
             inner, outer = self._separate_at_paren(expr)
@@ -941,7 +582,7 @@ class JSInterpreter(object):
                 if_expr, expr = self._separate_at_paren(expr)
             else:
                 # may lose ... else ... because of ll.368-374
-                if_expr, expr = self._separate_at_paren(' %s;' % (expr,), delim=';')
+                if_expr, expr = self._separate_at_paren(expr, delim=';')
             else_expr = None
             m = re.match(r'else\s*(?P<block>\{)?', expr)
             if m:
@@ -1079,7 +720,7 @@ class JSInterpreter(object):
             start, end = m.span()
             sign = m.group('pre_sign') or m.group('post_sign')
             ret = local_vars[var]
-            local_vars[var] = _js_add(ret, 1 if sign[0] == '+' else -1)
+            local_vars[var] += 1 if sign[0] == '+' else -1
             if m.group('pre_sign'):
                 ret = local_vars[var]
             expr = expr[:start] + self._dump(ret, local_vars) + expr[end:]
@@ -1089,18 +730,15 @@ class JSInterpreter(object):
 
         m = re.match(r'''(?x)
             (?P<assign>
-                (?P<out>{_NAME_RE})(?P<out_idx>(?:\[{_NESTED_BRACKETS}\])+)?\s*
+                (?P<out>{_NAME_RE})(?:\[(?P<index>[^\]]+?)\])?\s*
                 (?P<op>{_OPERATOR_RE})?
                 =(?!=)(?P<expr>.*)$
             )|(?P<return>
                 (?!if|return|true|false|null|undefined|NaN|Infinity)(?P<name>{_NAME_RE})$
-            )|(?P<attribute>
-                (?P<var>{_NAME_RE})(?:
-                    (?P<nullish>\?)?\.(?P<member>[^(]+)|
-                    \[(?P<member2>{_NESTED_BRACKETS})\]
-                )\s*
             )|(?P<indexing>
-                (?P<in>{_NAME_RE})(?P<in_idx>\[.+\])$
+                (?P<in>{_NAME_RE})\[(?P<idx>.+)\]$
+            )|(?P<attribute>
+                (?P<var>{_NAME_RE})(?:(?P<nullish>\?)?\.(?P<member>[^(]+)|\[(?P<member2>[^\]]+)\])\s*
             )|(?P<function>
                 (?P<fname>{_NAME_RE})\((?P<args>.*)\)$
             )'''.format(**globals()), expr)
@@ -1108,28 +746,19 @@ class JSInterpreter(object):
         if md.get('assign'):
             left_val = local_vars.get(m.group('out'))
 
-            if not m.group('out_idx'):
+            if not m.group('index'):
                 local_vars[m.group('out')] = self._operator(
                     m.group('op'), left_val, m.group('expr'), expr, local_vars, allow_recursion)
                 return local_vars[m.group('out')], should_return
             elif left_val in (None, JS_Undefined):
                 raise self.Exception('Cannot index undefined variable ' + m.group('out'), expr=expr)
 
-            indexes = md['out_idx']
-            while indexes:
-                idx, indexes = self._separate_at_paren(indexes)
-                idx = self.interpret_expression(idx, local_vars, allow_recursion)
-                if indexes:
-                    left_val = self._index(left_val, idx)
-            if isinstance(idx, float):
-                idx = int(idx)
-            if isinstance(left_val, list) and len(left_val) <= int_or_none(idx, default=-1):
-                # JS Array is a sparsely assignable list
-                # TODO: handle extreme sparsity without memory bloat, eg using auxiliary dict
-                left_val.extend((idx - len(left_val) + 1) * [JS_Undefined])
+            idx = self.interpret_expression(m.group('index'), local_vars, allow_recursion)
+            if not isinstance(idx, (int, float)):
+                raise self.Exception('List index %s must be integer' % (idx, ), expr=expr)
+            idx = int(idx)
             left_val[idx] = self._operator(
-                m.group('op'), self._index(left_val, idx) if m.group('op') else None,
-                m.group('expr'), expr, local_vars, allow_recursion)
+                m.group('op'), self._index(left_val, idx), m.group('expr'), expr, local_vars, allow_recursion)
             return left_val[idx], should_return
 
         elif expr.isdigit():
@@ -1147,34 +776,63 @@ class JSInterpreter(object):
             return _Infinity, should_return
 
         elif md.get('return'):
-            ret = local_vars[m.group('name')]
-            # challenge may try to force returning the original value
-            # use an optional internal var to block this
-            if should_return == 'return':
-                if '_ytdl_do_not_return' not in local_vars:
-                    return ret, True
-                return (ret, True) if ret != local_vars['_ytdl_do_not_return'] else (ret, False)
-            else:
-                return ret, should_return
+            return local_vars[m.group('name')], should_return
 
-        with compat_contextlib_suppress(ValueError):
+        try:
             ret = json.loads(js_to_json(expr))  # strict=True)
             if not md.get('attribute'):
                 return ret, should_return
+        except ValueError:
+            pass
 
         if md.get('indexing'):
             val = local_vars[m.group('in')]
-            indexes = m.group('in_idx')
-            while indexes:
-                idx, indexes = self._separate_at_paren(indexes)
-                idx = self.interpret_expression(idx, local_vars, allow_recursion)
-                val = self._index(val, idx)
-            return val, should_return
+            idx = self.interpret_expression(m.group('idx'), local_vars, allow_recursion)
+            return self._index(val, idx), should_return
 
-        separated = self._separate_at_op(expr)
-        if separated:
-            op, separated, right_expr = separated
-            return self._eval_operator(op, op.join(separated), right_expr, expr, local_vars, allow_recursion), should_return
+        for op, _ in self._all_operators():
+            # hackety: </> have higher priority than <</>>, but don't confuse them
+            skip_delim = (op + op) if op in '<>*?' else None
+            if op == '?':
+                skip_delim = (skip_delim, '?.')
+            separated = list(self._separate(expr, op, skip_delims=skip_delim))
+            if len(separated) < 2:
+                continue
+
+            right_expr = separated.pop()
+            # handle operators that are both unary and binary, minimal BODMAS
+            if op in ('+', '-'):
+                # simplify/adjust consecutive instances of these operators
+                undone = 0
+                separated = [s.strip() for s in separated]
+                while len(separated) > 1 and not separated[-1]:
+                    undone += 1
+                    separated.pop()
+                if op == '-' and undone % 2 != 0:
+                    right_expr = op + right_expr
+                elif op == '+':
+                    while len(separated) > 1 and set(separated[-1]) <= self.OP_CHARS:
+                        right_expr = separated.pop() + right_expr
+                    if separated[-1][-1:] in self.OP_CHARS:
+                        right_expr = separated.pop() + right_expr
+                # hanging op at end of left => unary + (strip) or - (push right)
+                left_val = separated[-1] if separated else ''
+                for dm_op in ('*', '%', '/', '**'):
+                    bodmas = tuple(self._separate(left_val, dm_op, skip_delims=skip_delim))
+                    if len(bodmas) > 1 and not bodmas[-1].strip():
+                        expr = op.join(separated) + op + right_expr
+                        if len(separated) > 1:
+                            separated.pop()
+                            right_expr = op.join((left_val, right_expr))
+                        else:
+                            separated = [op.join((left_val, right_expr))]
+                            right_expr = None
+                        break
+                if right_expr is None:
+                    continue
+
+            left_val = self.interpret_expression(op.join(separated), local_vars, allow_recursion)
+            return self._operator(op, left_val, right_expr, expr, local_vars, allow_recursion), should_return
 
         if md.get('attribute'):
             variable, member, nullish = m.group('var', 'member', 'nullish')
@@ -1195,15 +853,12 @@ class JSInterpreter(object):
             def eval_method(variable, member):
                 if (variable, member) == ('console', 'debug'):
                     if Debugger.ENABLED:
-                        Debugger.write(self.interpret_expression('[{0}]'.format(arg_str), local_vars, allow_recursion))
+                        Debugger.write(self.interpret_expression('[{}]'.format(arg_str), local_vars, allow_recursion))
                     return
                 types = {
                     'String': compat_str,
                     'Math': float,
                     'Array': list,
-                    'Date': self.JS_Date,
-                    'RegExp': self.JS_RegExp,
-                    # 'Error': self.Exception,  # has no std static methods
                 }
                 obj = local_vars.get(variable)
                 if obj in (JS_Undefined, None):
@@ -1211,7 +866,7 @@ class JSInterpreter(object):
                 if obj is JS_Undefined:
                     try:
                         if variable not in self._objects:
-                            self._objects[variable] = self.extract_object(variable, local_vars)
+                            self._objects[variable] = self.extract_object(variable)
                         obj = self._objects[variable]
                     except self.Exception:
                         if not nullish:
@@ -1249,105 +904,67 @@ class JSInterpreter(object):
                 if obj is compat_str:
                     if member == 'fromCharCode':
                         assertion(argvals, 'takes one or more arguments')
-                        return ''.join(compat_chr(int(n)) for n in argvals)
+                        return ''.join(map(compat_chr, argvals))
                     raise self.Exception('Unsupported string method ' + member, expr=expr)
                 elif obj is float:
                     if member == 'pow':
                         assertion(len(argvals) == 2, 'takes two arguments')
                         return argvals[0] ** argvals[1]
                     raise self.Exception('Unsupported Math method ' + member, expr=expr)
-                elif obj is self.JS_Date:
-                    return getattr(obj, member)(*argvals)
 
                 if member == 'split':
-                    assertion(len(argvals) <= 2, 'takes at most two arguments')
-                    if len(argvals) > 1:
-                        limit = argvals[1]
-                        assertion(isinstance(limit, int) and limit >= 0, 'integer limit >= 0')
-                        if limit == 0:
-                            return []
-                    else:
-                        limit = 0
-                    if len(argvals) == 0:
-                        argvals = [JS_Undefined]
-                    elif isinstance(argvals[0], self.JS_RegExp):
-                        # avoid re.split(), similar but not enough
-
-                        def where():
-                            for m in argvals[0].finditer(obj):
-                                yield m.span(0)
-                            yield (None, None)
-
-                        def splits(limit=limit):
-                            i = 0
-                            for j, jj in where():
-                                if j == jj == 0:
-                                    continue
-                                if j is None and i >= len(obj):
-                                    break
-                                yield obj[i:j]
-                                if jj is None or limit == 1:
-                                    break
-                                limit -= 1
-                                i = jj
-
-                        return list(splits())
-                    return (
-                        obj.split(argvals[0], limit - 1) if argvals[0] and argvals[0] != JS_Undefined
-                        else list(obj)[:limit or None])
+                    assertion(argvals, 'takes one or more arguments')
+                    assertion(len(argvals) == 1, 'with limit argument is not implemented')
+                    return obj.split(argvals[0]) if argvals[0] else list(obj)
                 elif member == 'join':
                     assertion(isinstance(obj, list), 'must be applied on a list')
-                    assertion(len(argvals) <= 1, 'takes at most one argument')
-                    return (',' if len(argvals) == 0 or argvals[0] in (None, JS_Undefined)
-                            else argvals[0]).join(
-                                ('' if x in (None, JS_Undefined) else _js_toString(x))
-                                for x in obj)
+                    assertion(len(argvals) == 1, 'takes exactly one argument')
+                    return argvals[0].join(obj)
                 elif member == 'reverse':
                     assertion(not argvals, 'does not take any arguments')
                     obj.reverse()
                     return obj
                 elif member == 'slice':
-                    assertion(isinstance(obj, (list, compat_str)), 'must be applied on a list or string')
-                    # From [1]:
-                    # .slice() - like [:]
-                    # .slice(n) - like [n:] (not [slice(n)]
-                    # .slice(m, n) - like [m:n] or [slice(m, n)]
-                    # [1] https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/slice
-                    assertion(len(argvals) <= 2, 'takes between 0 and 2 arguments')
-                    if len(argvals) < 2:
-                        argvals += (None,)
-                    return obj[slice(*argvals)]
+                    assertion(isinstance(obj, list), 'must be applied on a list')
+                    assertion(len(argvals) == 1, 'takes exactly one argument')
+                    return obj[argvals[0]:]
                 elif member == 'splice':
                     assertion(isinstance(obj, list), 'must be applied on a list')
                     assertion(argvals, 'takes one or more arguments')
                     index, how_many = map(int, (argvals + [len(obj)])[:2])
                     if index < 0:
                         index += len(obj)
-                    res = [obj.pop(index)
-                           for _ in range(index, min(index + how_many, len(obj)))]
-                    obj[index:index] = argvals[2:]
+                    add_items = argvals[2:]
+                    res = []
+                    for _ in range(index, min(index + how_many, len(obj))):
+                        res.append(obj.pop(index))
+                    for i, item in enumerate(add_items):
+                        obj.insert(index + i, item)
                     return res
-                elif member in ('shift', 'pop'):
-                    assertion(isinstance(obj, list), 'must be applied on a list')
-                    assertion(not argvals, 'does not take any arguments')
-                    return obj.pop(0 if member == 'shift' else -1) if len(obj) > 0 else JS_Undefined
                 elif member == 'unshift':
                     assertion(isinstance(obj, list), 'must be applied on a list')
-                    # not enforced: assertion(argvals, 'takes one or more arguments')
-                    obj[0:0] = argvals
-                    return len(obj)
+                    assertion(argvals, 'takes one or more arguments')
+                    for item in reversed(argvals):
+                        obj.insert(0, item)
+                    return obj
+                elif member == 'pop':
+                    assertion(isinstance(obj, list), 'must be applied on a list')
+                    assertion(not argvals, 'does not take any arguments')
+                    if not obj:
+                        return
+                    return obj.pop()
                 elif member == 'push':
-                    # not enforced: assertion(argvals, 'takes one or more arguments')
+                    assertion(argvals, 'takes one or more arguments')
                     obj.extend(argvals)
-                    return len(obj)
+                    return obj
                 elif member == 'forEach':
                     assertion(argvals, 'takes one or more arguments')
-                    assertion(len(argvals) <= 2, 'takes at most 2 arguments')
+                    assertion(len(argvals) <= 2, 'takes at-most 2 arguments')
                     f, this = (argvals + [''])[:2]
                     return [f((item, idx, obj), {'this': this}, allow_recursion) for idx, item in enumerate(obj)]
                 elif member == 'indexOf':
                     assertion(argvals, 'takes one or more arguments')
-                    assertion(len(argvals) <= 2, 'takes at most 2 arguments')
+                    assertion(len(argvals) <= 2, 'takes at-most 2 arguments')
                     idx, start = (argvals + [0])[:2]
                     try:
                         return obj.index(idx, start)
@@ -1356,7 +973,7 @@ class JSInterpreter(object):
                 elif member == 'charCodeAt':
                     assertion(isinstance(obj, compat_str), 'must be applied on a string')
                     # assertion(len(argvals) == 1, 'takes exactly one argument') # but not enforced
-                    idx = argvals[0] if len(argvals) > 0 and isinstance(argvals[0], int) else 0
+                    idx = argvals[0] if isinstance(argvals[0], int) else 0
                     if idx >= len(obj):
                         return None
                     return ord(obj[idx])
@@ -1365,8 +982,7 @@ class JSInterpreter(object):
                     assertion(len(argvals) == 2, 'takes exactly two arguments')
                     # TODO: argvals[1] callable, other Py vs JS edge cases
                     if isinstance(argvals[0], self.JS_RegExp):
-                        # access JS member with Py reserved name
-                        count = 0 if self._index(argvals[0], 'global') else 1
+                        count = 0 if argvals[0].flags & self.JS_RegExp.RE_FLAGS['g'] else 1
                         assertion(member != 'replaceAll' or count == 0,
                                   'replaceAll must be called with a global RegExp')
                         return argvals[0].sub(argvals[1], obj, count=count)
@@ -1407,8 +1023,8 @@ class JSInterpreter(object):
         for v in self._separate(list_txt):
             yield self.interpret_expression(v, local_vars, allow_recursion)
 
-    def extract_object(self, objname, *global_stack):
-        _FUNC_NAME_RE = r'''(?:{n}|"{n}"|'{n}')'''.format(n=_NAME_RE)
+    def extract_object(self, objname):
+        _FUNC_NAME_RE = r'''(?:[a-zA-Z$0-9]+|"[a-zA-Z$0-9]+"|'[a-zA-Z$0-9]+')'''
         obj = {}
         fields = next(filter(None, (
             obj_m.group('fields') for obj_m in re.finditer(
@@ -1428,8 +1044,7 @@ class JSInterpreter(object):
                 fields):
             argnames = self.build_arglist(f.group('args'))
             name = remove_quotes(f.group('key'))
-            obj[name] = function_with_repr(
-                self.build_function(argnames, f.group('code'), *global_stack), 'F<{0}>'.format(name))
+            obj[name] = function_with_repr(self.build_function(argnames, f.group('code')), 'F<{0}>'.format(name))
 
         return obj
 
@@ -1461,31 +1076,27 @@ class JSInterpreter(object):
         code, _ = self._separate_at_paren(func_m.group('code'))  # refine the match
         return self.build_arglist(func_m.group('args')), code
 
-    def extract_function(self, funcname, *global_stack):
+    def extract_function(self, funcname):
         return function_with_repr(
-            self.extract_function_from_code(*itertools.chain(
-                self.extract_function_code(funcname), global_stack)),
+            self.extract_function_from_code(*self.extract_function_code(funcname)),
             'F<%s>' % (funcname,))
 
     def extract_function_from_code(self, argnames, code, *global_stack):
         local_vars = {}
-
-        start = None
         while True:
-            mobj = re.search(r'function\((?P<args>[^)]*)\)\s*{', code[start:])
+            mobj = re.search(r'function\((?P<args>[^)]*)\)\s*{', code)
             if mobj is None:
                 break
-            start, body_start = ((start or 0) + x for x in mobj.span())
+            start, body_start = mobj.span()
             body, remaining = self._separate_at_paren(code[body_start - 1:])
             name = self._named_object(local_vars, self.extract_function_from_code(
                 [x.strip() for x in mobj.group('args').split(',')],
                 body, local_vars, *global_stack))
             code = code[:start] + name + remaining
-
         return self.build_function(argnames, code, local_vars, *global_stack)
 
-    def call_function(self, funcname, *args, **kw_global_vars):
-        return self.extract_function(funcname)(args, kw_global_vars)
+    def call_function(self, funcname, *args):
+        return self.extract_function(funcname)(args)
 
     @classmethod
     def build_arglist(cls, arg_text):
@@ -1504,9 +1115,8 @@ class JSInterpreter(object):
         global_stack = list(global_stack) or [{}]
         argnames = tuple(argnames)
 
-        def resf(args, kwargs=None, allow_recursion=100):
-            kwargs = kwargs or {}
-            global_stack[0].update(zip_longest(argnames, args, fillvalue=JS_Undefined))
+        def resf(args, kwargs={}, allow_recursion=100):
+            global_stack[0].update(zip_longest(argnames, args, fillvalue=None))
             global_stack[0].update(kwargs)
             var_stack = LocalNameSpace(*global_stack)
             ret, should_abort = self.interpret_statement(code.replace('\n', ' '), var_stack, allow_recursion - 1)
diff --git a/youtube_dl/utils.py b/youtube_dl/utils.py
index c4262936e..ac1e78002 100644
--- a/youtube_dl/utils.py
+++ b/youtube_dl/utils.py
@@ -4204,16 +4204,12 @@ def lowercase_escape(s):
         s)
 
 
-def escape_rfc3986(s, safe=None):
+def escape_rfc3986(s):
     """Escape non-ASCII characters as suggested by RFC 3986"""
     if sys.version_info < (3, 0):
         s = _encode_compat_str(s, 'utf-8')
-        if safe is not None:
-            safe = _encode_compat_str(safe, 'utf-8')
-    if safe is None:
-        safe = b"%/;:@&=+$,!~*'()?#[]"
     # ensure unicode: after quoting, it can always be converted
-    return compat_str(compat_urllib_parse.quote(s, safe))
+    return compat_str(compat_urllib_parse.quote(s, b"%/;:@&=+$,!~*'()?#[]"))
 
 
 def escape_url(url):
diff --git a/youtube_dl/version.py b/youtube_dl/version.py
index c70d9d2af..b82fbc702 100644
--- a/youtube_dl/version.py
+++ b/youtube_dl/version.py
@@ -1,3 +1,3 @@
 from __future__ import unicode_literals
 
-__version__ = '2025.04.07'
+__version__ = '2021.12.17'