[ie/youtube] Add `request_no_ads` extractor-arg (#15145)

Default is `true` for unauthenticated users.
Default is `false` if logged-in cookies have been passed to yt-dlp.
Using `true` results in a loss of premium formats.

Closes #15144
Authored by: WhatAmISupposedToPutHere

README.md

@@ -1871,6 +1871,7 @@ The following extractors use this feature:
 * `pot_trace`: Enable debug logging for PO Token fetching. Either `true` or `false` (default)
 * `fetch_pot`: Policy to use for fetching a PO Token from providers. One of `always` (always try fetch a PO Token regardless if the client requires one for the given context), `never` (never fetch a PO Token), or `auto` (default; only fetch a PO Token if the client requires one for the given context)
 * `jsc_trace`: Enable debug logging for JS Challenge fetching. Either `true` or `false` (default)
+* `request_no_ads`: Skip preroll ads to eliminate the mandatory wait period before download. Either `true` (the default if unauthenticated) or `false`. The default is `false` when logged-in cookies have been passed to yt-dlp, since `true` will result in a loss of premium formats
 
 #### youtube-ejs
 * `jitless`: Run suported Javascript engines in JIT-less mode. Supported runtimes are `deno`, `node` and `bun`. Provides better security at the cost of performance/speed. Do note that `node` and `bun` are still considered unsecure. Either `true` or `false` (default)

yt_dlp/extractor/youtube/_video.py

@@ -2628,18 +2628,29 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
     def _get_checkok_params():
         return {'contentCheckOk': True, 'racyCheckOk': True}
 
-    @classmethod
-    def _generate_player_context(cls, sts=None):
+    def _generate_player_context(self, sts=None):
         context = {
             'html5Preference': 'HTML5_PREF_WANTS',
         }
         if sts is not None:
             context['signatureTimestamp'] = sts
+
+        playback_context = {
+            'contentPlaybackContext': context,
+        }
+
+        # The 'adPlaybackContext'/'request_no_ads' workaround results in a loss of premium formats.
+        # Only default to 'true' if the user is unauthenticated, since we can't reliably detect all
+        # types of premium accounts (e.g. YTMusic Premium), and since premium users don't have ads.
+        default_arg_value = 'false' if self.is_authenticated else 'true'
+        if self._configuration_arg('request_no_ads', [default_arg_value])[0] != 'false':
+            playback_context['adPlaybackContext'] = {
+                'pyv': True,
+            }
+
         return {
-            'playbackContext': {
-                'contentPlaybackContext': context,
-            },
-            **cls._get_checkok_params(),
+            'playbackContext': playback_context,
+            **self._get_checkok_params(),
         }
 
     def _get_config_po_token(self, client: str, context: _PoTokenContext):