[extractor/youtube] Add `ios` to default clients used

* IOS is affected neither by 403 or by nsig so helps mitigate them preemptively
* IOS also has higher bit-rate "premium" formats though they are not labeled as such

README.md

@@ -1798,7 +1798,7 @@ The following extractors use this feature:
 #### 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`, `android` and `ios` with variants `_music`, `_embedded`, `_embedscreen`, `_creator` (e.g. `web_embedded`); and `mweb` and `tv_embedded` (agegate bypass) with no variants. By default, `android,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. 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`, `android` and `ios` with variants `_music`, `_embedded`, `_embedscreen`, `_creator` (e.g. `web_embedded`); and `mweb` and `tv_embedded` (agegate bypass) with no variants. By default, `ios,android,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. 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
 * `comment_sort`: `top` or `new` (default) - choose comment sorting mode (on YouTube's side)
 * `max_comments`: Limit the amount of comments to gather. Comma-separated list of integers representing `max-comments,max-parents,max-replies,max-replies-per-thread`. Default is `all,all,all,all`

yt_dlp/extractor/youtube.py

@@ -258,7 +258,7 @@ def build_innertube_clients():
     THIRD_PARTY = {
         'embedUrl': 'https://www.youtube.com/',  # Can be any valid URL
     }
-    BASE_CLIENTS = ('android', 'web', 'tv', 'ios', 'mweb')
+    BASE_CLIENTS = ('ios', 'android', 'web', 'tv', 'mweb')
     priority = qualities(BASE_CLIENTS[::-1])
 
     for client, ytcfg in tuple(INNERTUBE_CLIENTS.items()):
@@ -3625,7 +3625,7 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
 
     def _get_requested_clients(self, url, smuggled_data):
         requested_clients = []
-        default = ['android', 'web']
+        default = ['ios', 'android', 'web']
         allowed_clients = sorted(
             (client for client in INNERTUBE_CLIENTS.keys() if client[:1] != '_'),
             key=lambda client: INNERTUBE_CLIENTS[client]['priority'], reverse=True)
@@ -3932,6 +3932,10 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
             elif itag:
                 f['format_id'] = itag
 
+            if itag in ('616', '235'):
+                f['format_note'] = join_nonempty(f.get('format_note'), 'Premium', delim=' ')
+                f['source_preference'] = (f.get('source_preference') or -1) + 100
+
             f['quality'] = q(itag_qualities.get(try_get(f, lambda f: f['format_id'].split('-')[0]), -1))
             if f['quality'] == -1 and f.get('height'):
                 f['quality'] = q(res_qualities[min(res_qualities, key=lambda x: abs(x - f['height']))])