on Nov 17, 2015 at 1:18:29 pm Last Edited By Kalle Kannisto on Nov 17, 2015 at 1:19:32 pm
If you attach the hat on a stick and make it "dance" that way, as opposed to having the hat on a dancer's head, you'll have much less manual work ahead of you. If you paint the stick green and light it well, you may even be able to keylight the whole thing.
Once you have the basic motion, you can add more motion with audio-to-keyframes if need be.
Alternatives include getting a 3D model of a hat and animating it with C4D or Element 3D.