Edit: To clarify:
Is it even possible, financially speaking, to keep adding storage? I mean, advertisements don’t even make a lot of money, is the indefinite growth of server storage even sustainable?
Or will they do what Twitch does with old content and just delete them?
I’d say there’s a significant amount of storage available for cache. On the first transcoding the video is saved to cache so that the cached version can be streamed in the future. After enough time lapses or the cache becomes full, the cached video is deleted