[youtube:tab] Add `approximate_date` extractor-arg

README.md

@@ -1663,6 +1663,7 @@ The following extractors use this feature:
 
 #### youtubetab (YouTube playlists, channels, feeds, etc.)
 * `skip`: One or more of `webpage` (skip initial webpage download), `authcheck` (allow the download of playlists requiring authentication when no initial webpage is downloaded. This may cause unwanted behavior, see [#1122](https://github.com/yt-dlp/yt-dlp/pull/1122) for more details)
+* `approximate_date`: Extract approximate `upload_date` in flat-playlist. This may cause date-based filters to be slightly off
 
 #### funimation
 * `language`: Languages to extract. Eg: `funimation:language=english,japanese`

yt_dlp/extractor/youtube.py

@@ -844,7 +844,7 @@ class YoutubeBaseInfoExtractor(InfoExtractor):
             'uploader': uploader,
             'channel_id': channel_id,
             'thumbnails': thumbnails,
-            #  'upload_date': strftime_or_none(timestamp, '%Y%m%d'),
+            'upload_date': strftime_or_none(timestamp, '%Y%m%d') if self._configuration_arg('approximate_date', ie_key='youtubetab') else None,
             'live_status': ('is_upcoming' if scheduled_timestamp is not None
                             else 'was_live' if 'streamed' in time_text.lower()
                             else 'is_live' if overlay_style is not None and overlay_style == 'LIVE' or 'live now' in badges