Why Bieber's "Baby" beat Gaga's "Bad Romance"

This video by Justin Bieber has 251 MILLION views and is now the most viewed Youtube video of all time.

Lady Gaga's most watched video, on the other hand, still has to break the 248 million mark, even if it was posted a full three months BEFORE Bieber's.

WHY? 

Youtube's demographics, baby, that's all there is to it, as this post on Urlesque shows. 

Simply put, Lady Gaga's appeal is to a slightly older and smaller segment of the Youtube population. Teen girls, Bieber's base, apparently make up a much much bigger segment of Youtube.