This doesn't satisfy either requirement: "encrypted video stream" most importantly, but also "[using a] plain file host rather than hosting some custom service"

This doesn't satisfy either requirement: "encrypted video stream" most importantly, but also "[using a] plain file host rather than hosting some custom service" since a plain file host won't pull my https stream, I'll need to setup another service to do that. Or did I misunderstand what you meant? Either way, thanks for helping think of solutions!