I don’t think uploading any videos will be directly supported at any point in the future as it would put a lot of strain on the servers due to taking up a lot of storage space. This would result in higher server costs for the admins.
For now your best option is to just upload your videos to some place else (like PeerTube) and then post a link of it to Lemmy. For example, @sexy_peach has already done this multiple times when uploading Factorio gameplay.