Why are there dancing bears in so many music videos or people wearing the bear head on their heads?

http://www.youtube.com/watch?v=tatccHVfuhA

This is just a blind guess, but dancing bears are commonly associated with the circus. And the circus is commonly associated with the exotic, frightening, freakish, and unnatural. So maybe they're trying to add an element of that to their music videos?

The same thing happened in that 30 Seconds to Mars video that's a pastiche to The Shining. One of the band members is giving a blowj*b to a man in a bear costume. And it's supposed to be nightmarish and twisted other-worldly.

The Grateful Dead when I see dancing bears I think of them

Dancing bears: A series of stylized dancing bears was drawn by Bob Thomas as part of the back cover for the album History of the Grateful Dead, Volume One (Bear's Choice).[53] The bear is a reference to Owsley "Bear" Stanley, who recorded and produced the album. Bear himself wrote, "... the bears on the album cover are not really 'dancing'. I don't know why people think they are, their positions are quite obviously those of a high-stepping march."[54]

No idea...

To add to the list, "Never Let Me Go" by Family Force 5