X-posting this from the YouTube thread, as it's important info about some classic video uploads that are on there.
Today is the last day before YouTube privatizes all unlisted videos from before 2017 for some type of security update. In all honesty, this is pretty ridiculous of them to do, but I'm not all surprised to see they're doing some shenanigans that will cause some clips to possibly become lost media. Its so infuriating.
https://blog.youtube/news-and-events/update-youtube-unlisted-links/
Anywho, if you know of any videos you might've seen that are unlisted, what I'd recommend is to save them and have the name of the original uploader somewhere in the file name. That way, if you wanna reupload it, you can credit the person who originally posted it, but got the video privated because of YouTube's update. I wish it didn't come at a very inconvenient time for me, but alas