[Youtube] Fix private feeds/playlists on multi-channel accounts (#143)

Authored by: colethedj

yt_dlp/extractor/youtube.py

@@ -301,7 +301,6 @@ def _call_api(self, ep, query, video_id, fatal=True, headers=None,
         auth = self._generate_sapisidhash_header()
         if auth is not None:
             headers.update({'Authorization': auth, 'X-Origin': 'https://www.youtube.com'})
-
         return self._download_json(
             'https://www.youtube.com/youtubei/v1/%s' % ep,
             video_id=video_id, fatal=fatal, note=note, errnote=errnote,
@@ -2704,7 +2703,7 @@ def _extract_continuation(cls, renderer):
             ctp = continuation_ep.get('clickTrackingParams')
             return YoutubeTabIE._build_continuation_query(continuation, ctp)
 
-    def _entries(self, tab, identity_token, item_id):
+    def _entries(self, tab, item_id, identity_token, account_syncid):
 
         def extract_entries(parent_renderer):  # this needs to called again for continuation to work with feeds
             contents = try_get(parent_renderer, lambda x: x['contents'], list) or []
@@ -2764,6 +2763,10 @@ def extract_entries(parent_renderer):  # this needs to called again for continua
         if identity_token:
             headers['x-youtube-identity-token'] = identity_token
 
+        if account_syncid:
+            headers['X-Goog-PageId'] = account_syncid
+            headers['X-Goog-AuthUser'] = 0
+
         for page_num in itertools.count(1):
             if not continuation:
                 break
@@ -2883,7 +2886,7 @@ def _extract_uploader(data):
                         try_get(owner, lambda x: x['navigationEndpoint']['browseEndpoint']['canonicalBaseUrl'], compat_str))
         return {k: v for k, v in uploader.items() if v is not None}
 
-    def _extract_from_tabs(self, item_id, webpage, data, tabs, identity_token):
+    def _extract_from_tabs(self, item_id, webpage, data, tabs):
         playlist_id = title = description = channel_url = channel_name = channel_id = None
         thumbnails_list = tags = []
 
@@ -2947,7 +2950,10 @@ def _extract_from_tabs(self, item_id, webpage, data, tabs, identity_token):
             'channel_id': metadata['uploader_id'],
             'channel_url': metadata['uploader_url']})
         return self.playlist_result(
-            self._entries(selected_tab, identity_token, playlist_id),
+            self._entries(
+                selected_tab, playlist_id,
+                self._extract_identity_token(webpage, item_id),
+                self._extract_account_syncid(data)),
             **metadata)
 
     def _extract_mix_playlist(self, playlist, playlist_id):
@@ -3026,6 +3032,17 @@ def _extract_identity_token(self, webpage, item_id):
             r'\bID_TOKEN["\']\s*:\s*["\'](.+?)["\']', webpage,
             'identity token', default=None)
 
+    @staticmethod
+    def _extract_account_syncid(data):
+        """Extract syncId required to download private playlists of secondary channels"""
+        sync_ids = (
+            try_get(data, lambda x: x['responseContext']['mainAppWebResponseContext']['datasyncId'], compat_str)
+            or '').split("||")
+        if len(sync_ids) >= 2 and sync_ids[1]:
+            # datasyncid is of the form "channel_syncid||user_syncid" for secondary channel
+            # and just "user_syncid||" for primary channel. We only want the channel_syncid
+            return sync_ids[0]
+
     def _extract_webpage(self, url, item_id):
         retries = self._downloader.params.get('extractor_retries', 3)
         count = -1
@@ -3085,8 +3102,7 @@ def _real_extract(self, url):
         tabs = try_get(
             data, lambda x: x['contents']['twoColumnBrowseResultsRenderer']['tabs'], list)
         if tabs:
-            identity_token = self._extract_identity_token(webpage, item_id)
+            return self._extract_from_tabs(item_id, webpage, data, tabs)
-            return self._extract_from_tabs(item_id, webpage, data, tabs, identity_token)
 
         playlist = try_get(
             data, lambda x: x['contents']['twoColumnWatchNextResults']['playlist']['playlist'], dict)