Also, note that youtube is a terrible means of guaging the popularity of something. It shows the amount of times it's been played, not the number of people who like it, and it's not a great indicator of who likes it because, for instance, Minnie Ripperton's "Loving You" has been played at my office probably 200 times this year. Why? Because my Lt. Thinks it's funny to torment me with it. I think it's the worst song ever.
Same goes with Beiber or Rebecca Black or really any teen pop. People are tuning in either to A) see what the fuss is about or B) torment another human being with it now that they know. The only real exception seems to be Psy's "Gangam Style", which bears a striking resemblance to The Macerena to me. It was big stuff in 2012, in 2 years it'll just piss people off.