I have pinned video to IPFS, before, and it streamed well from an IPFS gateway. I lack an understanding of what the impact to a gateway would be, though, if many users were doing this.

One thought would be software that would automatically pin any video you viewed, or the partial content you viewed, for a period of time. Popular videos with many views per day would also be supported by many peers to pull from. Videos viewed infrequently might be pinned only by the content creator or a handful of others. The like/upvote concept could be tied into pinning, even on a scale such that an ordinary upvote would subscribe you to, say, 3 days of pinning, and a super-upvote would subscribe you to 20 days.

haven't tried since my comment, but no

I can't figure out where to enter credentials. Trying various menu options yields the message "Login first" - OK, but where?

I've been brainstorming things like this, too, and have come up with some similar thoughts. I think we can have both tags and communities. Suppose there's a trust model. A community on an instance will entrust certain members to whitelist posts that are in an approved list of tags. Anything on any instance that gets tagged with one of the approved tags would go into a queue. You could employ a bot to work the queue to eliminate low hanging fruit, and then trusted community members would work it to approve posts.

Likewise, an instance community could have a trust relationship with a community on a different instance. They could say, "Any posts approved by the cats community over there are automatically approved here." This could help distribute the load on the queue. As a side note, there would need to be logging of metadata so an audit trail could be analyzed in case problems arose in the trust circle.

So, that addresses a way to handle submissions. There's another ball of wax with comments. Ideally, a comment section would be a way for users to discover new communities. You might be reading comments on a #cat submission and see a comment from someone in #toebeans and go, "Oh hey, that looks interesting," and you can jump to the community and/or subscribe to it. It's not immediately obvious to me how an app could aggregate comments across multiple communities or if ActivityPub could facilitate it. Seems plausible.

I really hope we eventually get a richer platform out of all this. It's a great opportunity for people to put their heads together and think of new improvements.