The process is this: create a "page" on AO3 for your vid (like this one). [...] If the vid at the streaming site gets taken down, you can upload to another site and replace the link. But the feedback, kudos etc you get on A03 won't disappear and you'll only need to update your links in one place.

This is brilliant. This thing, right here, that you wrote, is amazing. I had been dithering and wondering what the big deal was about vids on AO3 and what the point was, and you completely sold me on it. I dunno if that was your goal with this, explaining the usefulness of the use case (vs just giving instructions on how to do it), but you were very successful. Thank you!