ArchiveTeam is trying to brute force the entire URL space before its too late. You can run a Virtualbox VM/docker image (ArchiveTeam Warrior) to help (unique IPs are needed). I've been running it for a couple months and found a million.
After a while I started to get "Google asks for a login" errors. Should I just keep going? There's no indication on what I should do on the ArchiveTeam wiki
Thanks for sharing this. I've often felt that the ease by which we can erase digital content makes our time period susceptible to a digital dark ages to archaeologists studying history a few thousand years from now.
Us preserving digital archives is a good step. I guess making hard copies would be the next step.
https://wiki.archiveteam.org/index.php/ArchiveTeam_Warrior