[youtube] Transform google's JSON dialect (fixes #2663)

youtube_dl/extractor/youtube.py

@@ -1446,7 +1446,9 @@ class YoutubePlaylistIE(YoutubeBaseInfoExtractor):
                 break
 
             more = self._download_json(
-                'https://youtube.com/%s' % mobj.group('more'), playlist_id, 'Downloading page #%s' % page_num)
+                'https://youtube.com/%s' % mobj.group('more'), playlist_id,
+                'Downloading page #%s' % page_num,
+                transform_source=uppercase_escape)
             content_html = more['content_html']
             more_widget_html = more['load_more_widget_html']