The tagging is even harder than the storage. There might well be high quality footage of live music from not much less than 100 years ago sitting on film reels in a shed somewhere - my university's library had a whole basement of pre-1850 books that they just hadn't had time to catalogue yet.
The idea is that a future person could freely deep dive through a rich well indexed history of media about whatever specifically interests them
I wish people would stop trying to assess the value of a given piece of media and just tag and archive the stuff.
For instance, high quality footage of live music from 100 years ago would be very interesting to some.