alt Hacker NewsVideos do disappear, though. https://www.reddit.com/r/DataHoarder/comments/1ioz4x1/is_it_...
Searching hn.algolia.com for examples will yield numerous ones.
https://news.ycombinator.com/item?id=23758547
https://bsky.app/profile/sinevibes.bsky.social/post/3lhazuyn...
Of course videos disappear for copyright, ToS violations, or when the uploaders remove them. They do not disappear just because nobody watched them.