I think this idea isn’t the best solution, and will never happen because of that. But just in case I’m wrong…
What if everyone using a YouTube-like app to upload content only uploaded one version, like with actual YouTube? This version, say, a 1920x1080 VP9 at 60fps with 96 kHz FLAC, would be the definitive version of the video.
If someone wanted to watch videos in 1366x768 AV1 at 30fps with 48 kHz Opus, they could set this as their preference, and the app could automatically transcode any video they find not in that format and upload it.
This would mean that, assuming the viewer has a mainstream preference of codecs, most of the videos they watch would already by transcoded suitably by another user with similar settings, but occasionally they will be the first transcoder. This first transcoder would unavoidably have to bear the PUT cost of uploading it so that the new video file could be put into the app’s database.
Some users could set the app to transcode even when their preferred codecs are present, and submit the new video file to the app’s database. Assuming the transcoding and upload requirements are strict enough, this new video file would be bit identical to previous users’ uploads, and therefore not incur a PUT cost. When the user submits this video to the app’s database, the database would confirm that the user does (co-)own the video file, and add 1 to the number of verifications. If a user attempted to upload a version with embedded adverts or some other malicious addition, that version would never get verified by other uploaders.
A transcoded video with ads could be mass verified by a bot network, which is the point at which my idea fails. Maybe a Web of Trust could sort that problem out? Or, maybe the app could accept safecoin payment to transcode the video for the first user requesting the different format, which it would achieve by using that safecoin to pay a verifiable distributed computing network running within SAFE?
As it stands, I think the inevitable YouTube-like app will just default to uploading the original file along with several popular formats.