@paul @Gargron @selea The obvious solution is to create different versions of the video server-side.
This is a major advantage that proprietary social networks have over Mastodon—and I think a big deal in holding up adoption.
Unfortunately I don't know how to solve this issue without overloading small instances and servers with work. Only idea I have is to outsource transcoding to volunteers, and do it on their devices/computers and write back transcoded media to original server.