GET /api/search/related/{video_id} reads the list YouTube shows beside a
video from the website's InnerTube "next" endpoint (no quota), and brings
it into the catalog the way live-search results come in. It leaves out
what the user watched or hid, here or in their Takeout history (unless
taken back to "new" since), blocked channels and the video itself, and
pages on until 20 are gathered (at most 4 pages). region=topical|hu picks
the locale the list is filled in. Its own per-user daily cap
(related_daily_limit_per_user, one event per opened list); a failed
scrape answers 422 youtube/unavailable.
The InnerTube request (live key, consent cookie, errors) moves into
youtube/innertube.py, shared by the search scrape and the related one.
peter
8b37c470ba