The Accidental Railfan: The Lost Videos
These "lost" videos were made back in the 1990s, and thought to have been destroyed. Recently rediscovered, they're all that survive of a once extensive library, comprising roughly 500 hours of material. Video quality is relatively poor owing to being down several generations*, but that doesn't diminish the information value. Some things and places in them no longer exist.
*Super Betamax videotape original > Super Betamax dub > VHS dupe > DVD conversion > digital dupe > digital edit uploaded