I’ll try hosting video on my ~700Mb up line (IIRC) to see how it works if I get the howtos.

It looks like that if you set up a lemmy instance, there's an upload size cap for things that people can attach.

https://github.com/LemmyNet/lemmy/issues/3349

If you set that to some insane number, I imagine that people can upload large stuff, and as I note below, at least webm files seem to be doable right now on lemmy.world (just that the lemmy.world size cap is going to keep someone from uploading anything of meaningful size). I'd imagine that if you lift that cap to whatever you want -- if you want full-length movies, then probably a couple of gigabytes -- the users of your instance should be able to upload. They'd click on "image" rather than "movie", but...shrugs

The Lemmy Web UI isn't really designed for huge uploads, doesn't show a progress bar, so it's probably not going to provide the best user experience, but I'd expect that it'll work.

If you don't want to run a lemmy instance, but do want to permit people to just anonymously upload files that they can link to on other lemmy instances, then while I don't have a particular example ready to hand, I'm sure that there are no shortage of web-based "dropbox" systems that let one upload and then serve files. Just have people reference the file's URL the way they would anything else.

If you want to run a PeerTube instance, which is aimed at fediverse video sharing, then I'd look at their docs. I've never set one up, but I'm sure that they have some kind of documentation.