@atomicpoet This is something I stumbled into just a few weeks ago, and not even with video content.
There was this service that let you set up free web forums (EZboards) that was very popular around the turn of the millenium. The web forums were originally preserved on the Internet Archive, but the domain was picked up by a malicious squatter in 2011.
Thanks to a retroactive robots.txt that forbids archiving, those archives are lost now. And that's just HTML and pictures, not something weighty like video.