338573b1e8
youtube-transcript-api v1.2.4 returns XML parse error on empty response for ALL videos in this campaign. yt-dlp's --write-auto-subs reliably returns 1000s of segments per video. Switched to yt-dlp as the primary path. Tests updated to mock _fetch_via_ytdlp instead of _fetch_raw_transcript. 8/8 tests passing.