Does anyone else find it weird that most (all?) of the youtube videos referenced in the "Cultural Impact" section of that Wikipedia article are now private? I'm not saying that united paid anyone to make their videos private, but it's definitely not a good look now. Even a 404 or video not found would be better IMHO.
The key did get loose. Thousands of engineers had access to it and it showed up on dark corners of the internet for sale. A bunch of my unlisted videos got more view counts than they ought to have had, so I think abuse of it was pretty widespread.
They only changed it for the videos with vulnerable URLs. Do you really think it's better for all those videos to become effectively listed?
Maybe they could have done something more clever, like only private videos that aren't linked on the public web already, but there would still need to be a mass privating of most unlisted videos.