There's lots of old stuff on YouTube from long dead small channels. This stuff rots and disappears over time with nobody around to maintain it. I guess it's a good reminder that everything needs maintenance.
Something similar, but much more dramatic, happened once they got rid of annotations - lots of old stuff that no longer works the way it was intended.
It seems like nobody particularly cares about preserving this kind of stuff. It's a big downside to having content that only lives on the web - video files on my local storage don't just change retroactively. Things might still need maintenance, like getting old flash files to work again, but information doesn't get lost as easily.