There is already something like this via the Wayback Machine (who indeed do copies of video media but more typically VHS and other things) and things like the Russian Library genesis, which is kept in torrent format.
The problem really is that storage for video media is insane compared to storage of document or even photo data.
If people here haven’t read into it, it’s incredibly interesting to look into the way the Internet Archive works. In particular you have to begin to concern yourselves with how long it takes for HDs, SSDs, and other media to degrade in time.