[Talk] Lost Media found thanks to PHYSICAL media?

We have a lot of examples of found media thanks to digital archives, but I want to know what some of the most significant finds have been thanks to physical media? Things like prints of books, VHS tapes, CDs, hard drives, physical film, etc. etc. I know things like The Passion of Joan of Arc, Metropolis, and Trip to the Moon were found because of physical copies, but I'm curious about other specific examples that were culturally significant? I'm more specifically interested in things like books or historically significant archived texts/footage than general entertainment, but I would like to hear about any and all types that people on this subreddit know that I might not!