Remix permissions

Found under a video's details in Studio, with three positions: allow video and audio, allow audio only, or turn remixing off. Everything is switched on by default, and a remix carries a link back to the source video, so leaving it on is a distribution channel other people build for you. The part creators miss is that the setting only covers long-form videos. Publish a Short and it becomes remixable automatically, with no per-video opt-out available through ordinary Studio access.