I was just reminiscing of the early internet elsewhere, and I randomly remembered https://joecartoon.com/. Crazily enough, the site is still running! I must have watched every single flash animation on that entire website as a teenager.
Unfortunately flash is dead, so they seem to all be regular videos now, but at least the content is still there. I just watched the gerbil in a fish tank one myself. I’m guessing they’re just screen recordings of the author clicking through the options