Dobbsfox is certainly right that this is not completely a game of chance. But I think Alex-Caple states the counter argument well: Videos are not uploaded into a fair environment where they all have an opportunity to become popular if they are deserving. I love Charlie Bit Me as much as the next guy--maybe I should have disclosed that 50 of those 104 million views are mine--but one has to imagine that equally adorable things continue to languish in obscurity.

Regarding Vimeo, my colleague Farhad wrote a good piece a few months ago on its curiously high quality. They do seem to have fostered an environment based on artistry, which is the dream of many a webmaster. This very well may preclude them from ever reaching YouTube's gargantuan size. Given the overhead, they probably don't want to.