[ie/youtube] Fix signature and nsig extraction for player `4fcd6e4a` (#12748)

Closes #12746
Authored by: seproDev

test/test_youtube_signature.py

@@ -88,6 +88,11 @@ _SIG_TESTS = [
         '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',
+    ),
 ]
 
 _NSIG_TESTS = [
@@ -243,6 +248,10 @@ _NSIG_TESTS = [
         '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',
+    ),
 ]
 
 

yt_dlp/extractor/youtube/_video.py

@@ -2182,6 +2182,7 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
                     (?P<value>
                         (?P<q2>["\'])(?:(?!(?P=q2)).|\\.)+(?P=q2)
                         \.split\((?P<q3>["\'])(?:(?!(?P=q3)).)+(?P=q3)\)
+                        |\[\s*(?:(?P<q4>["\'])(?:(?!(?P=q4)).|\\.)*(?P=q4)\s*,?\s*)+\]
                     )
                 )[;,]
             ''', jscode, 'global variable', group=('code', 'name', 'value'), default=(None, None, None))
@@ -2199,7 +2200,7 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
 
     def _extract_n_function_code(self, video_id, player_url):
         player_id = self._extract_player_info(player_url)
-        func_code = self.cache.load('youtube-nsig', player_id, min_ver='2025.03.25')
+        func_code = self.cache.load('youtube-nsig', player_id, min_ver='2025.03.26')
         jscode = func_code or self._load_player(video_id, player_url)
         jsi = JSInterpreter(jscode)