From Homestar Runner to Salad fingers to badgers, stick figure battles, and the End of Ze World, this — dare I call it an artform? — was a cultural touchstone for a generation.
Flash made vector animation available to the masses, and internet distribution of the relatively small video files was a piece of cake. With the filetype now essentially deprecated, the creators gone on to bigger and better things, the distribution sites shut down, it is a dead form. Most of it will be lost forever, although there may be someone archiving some of it for posterity.
hBomberGuy did a long video on Newgrounds! It’s amazing, but I think it might only be on his Patreon.