Fix regex for other variable declaration type

This now supports declarations like `window["ytInitialData"] = ...` and `var ytInitialData = ...`

youtube_dl/extractor/youtube.py

@@ -3313,7 +3313,7 @@ class YoutubeFeedsInfoExtractor(YoutubeBaseInfoExtractor):
     Subclasses must define the _FEED_NAME and _PLAYLIST_TITLE properties.
     """
     _LOGIN_REQUIRED = True
-    _FEED_DATA = r'window\[\"ytInitialData\"\]\W?=\W?({.*?});'
+    _FEED_DATA = r'(?:window\["ytInitialData"\]|ytInitialData)\W?=\W?({.*?});'
     _YTCFG_DATA = r"ytcfg.set\(({.*?})\)"
 
     @property