From the YouTube description:
This video is awesome only because it is 8am in Jersey City, sitting on a bus filled with people on their way to work and this guy is belting Katy Perry California Girls with a disc man in hand. It was pretty much the best bus ride ever!
Those are exactly all of the reasons that this is awesome and it looks like it probably WAS pretty much the best bus ride ever! (Thanks for the tip, FrankLloydWrong and @andymated.)