Meanwhile, there's examples of long lost footage being found again precisely because people were recording/copying/pirating for their own purposes. I'm thinking explicitly of Doctor Who footage that the BBC overwrote (tape was expensive), but years later was found on privately recorded video tapes left in someone's shed.

Personally, I enjoy pirating less well-known scifi/horror films and series. It's surprising how relatively recent productions can "disappear" when there's no streaming company interested in it. My usual example of disappearing TV is the third season of "Monkey Dust". The music rights weren't agreed, so the third season never made it to DVD and is impossible to watch legally, but hopefully people like me will keep it available nonetheless.

There's also companies that like to censor previous output, such as Disney and their pro-Nazi propaganda.