I think it spread because the song is just so catchy, the video is quite quirky and weird, and so it's really just something that's likely to be shared casually

I think it spread because the song is just so catchy, the video is quite quirky and weird, and so it's really just something that's likely to be shared casually. Very established social-networking sites enable even quicker sharing and spreading of these videos than just a few years ago. Same deal as Gangnam Style pretty much.