Yeah, I don't get this mindset from content creators. It doesn't have to be some big thing if they're worried about losing viewers and money.
Bare minimum: Uploading a video to Youtube, a Peertube instance, and to Archive.org isn't much more work than just uploading to Youtube. Put links to all three in every description with the note that video mirrors are available at these following places.
I think the real issue is that giving up Youtube means giving up a revenue stream. Not a ton of people make video content just to create stuff anymore.
It is true, one of the devs explicitly confirmed it on bluesky, posted to this comm already here: https://lemmy.world/post/30881826