[youtube] Fix authentication (closes #11270)

youtube_dl/extractor/youtube.py

@@ -116,6 +116,8 @@ class YoutubeBaseInfoExtractor(InfoExtractor):
                 'f.req': json.dumps(f_req),
                 'flowName': 'GlifWebSignIn',
                 'flowEntry': 'ServiceLogin',
+                # TODO: reverse actual botguard identifier generation algo
+                'bgRequest': '["identifier",""]',
             })
             return self._download_json(
                 url, None, note=note, errnote=errnote,