[ie/youtube] Fix age-verification workaround (#10610)

Authored by: bashonly, Grub4K

Co-authored-by: Simon Sawicki <contact@grub4k.xyz>

README.md

@@ -1767,7 +1767,7 @@ # EXTRACTOR ARGUMENTS
 #### youtube
 * `lang`: Prefer translated metadata (`title`, `description` etc) of this language code (case-sensitive). By default, the video primary language metadata is preferred, with a fallback to `en` translated. See [youtube.py](https://github.com/yt-dlp/yt-dlp/blob/c26f9b991a0681fd3ea548d535919cec1fbbd430/yt_dlp/extractor/youtube.py#L381-L390) for list of supported content language codes
 * `skip`: One or more of `hls`, `dash` or `translated_subs` to skip extraction of the m3u8 manifests, dash manifests and [auto-translated subtitles](https://github.com/yt-dlp/yt-dlp/issues/4090#issuecomment-1158102032) respectively
-* `player_client`: Clients to extract video data from. The main clients are `web`, `ios` and `android`, with variants `_music` and `_creator` (e.g. `web_creator`); and `mediaconnect`, `mweb`, `android_producer`, `android_testsuite`, `android_vr`, `web_safari`, `web_embedded`, `tv` and `tv_embedded` with no variants. By default, `ios,web` is used, but `tv_embedded` and `_creator` variants are added as required for age-gated videos. Similarly, the music variants are added for `music.youtube.com` urls. Most `android` clients will be given lowest priority since their formats are broken. You can use `all` to use all the clients, and `default` for the default clients.
+* `player_client`: Clients to extract video data from. The main clients are `web`, `ios` and `android`, with variants `_music` and `_creator` (e.g. `ios_creator`); and `mediaconnect`, `mweb`, `android_producer`, `android_testsuite`, `android_vr`, `web_safari`, `web_embedded`, `tv` and `tv_embedded` with no variants. By default, `ios,web` is used, but `tv_embedded`, `web_creator` and `mediaconnect` are added as required for age-gated videos. Similarly, the music variants are added for `music.youtube.com` urls. Most `android` clients will be given lowest priority since their formats are broken. You can use `all` to use all the clients, and `default` for the default clients.
 * `player_skip`: Skip some network requests that are generally needed for robust extraction. One or more of `configs` (skip client configs), `webpage` (skip initial webpage), `js` (skip js player). While these options can help reduce the number of requests needed or avoid some rate-limiting, they could cause some issues. See [#860](https://github.com/yt-dlp/yt-dlp/pull/860) for more details
 * `player_params`: YouTube player parameters to use for player requests. Will overwrite any default ones set by yt-dlp.
 * `comment_sort`: `top` or `new` (default) - choose comment sorting mode (on YouTube's side)

yt_dlp/extractor/youtube.py

@@ -3854,14 +3854,28 @@ def append_client(*client_names):
                     f[STREAMING_DATA_CLIENT_NAME] = name
                 prs.append(pr)
 
-            # creator clients can bypass AGE_VERIFICATION_REQUIRED if logged in
+            # tv_embedded can work around age-gate and age-verification IF the video is embeddable
-            if variant == 'tv_embedded' and self._is_unplayable(pr) and self.is_authenticated:
+            if self._is_agegated(pr) and variant != 'tv_embedded':
-                append_client(f'{base_client}_creator')
-            elif variant != 'tv_embedded' and self._is_agegated(pr):
-                if self.is_authenticated:
-                    append_client(f'{base_client}_creator')
                 append_client(f'tv_embedded.{base_client}')
 
+            # Unauthenticated users will only get tv_embedded client formats if age-gated
+            if self._is_agegated(pr) and not self.is_authenticated:
+                self.to_screen(
+                    f'{video_id}: This video is age-restricted; some formats may be missing '
+                    f'without authentication. {self._login_hint()}', only_once=True)
+
+            # EU countries require age-verification for accounts to access age-restricted videos
+            # If account is not age-verified, _is_agegated() will be truthy for non-embedded clients
+            # If embedding is disabled for the video, _is_unplayable() will be truthy for tv_embedded
+            embedding_is_disabled = variant == 'tv_embedded' and self._is_unplayable(pr)
+            if self.is_authenticated and (self._is_agegated(pr) or embedding_is_disabled):
+                self.to_screen(
+                    f'{video_id}: This video is age-restricted and YouTube is requiring '
+                    'account age-verification; some formats may be missing', only_once=True)
+                # web_creator and mediaconnect can work around the age-verification requirement
+                # _producer, _testsuite, & _vr variants can also work around age-verification
+                append_client('web_creator', 'mediaconnect')
+
         if skipped_clients:
             self.report_warning(
                 f'Skipping player responses from {"/".join(skipped_clients)} clients '