This is a remarkable video. Snowball actually dances. The video is rather long, over 4 minutes, but if you take the time to view it entirely, you'll see Snowball change beats and gyrations, according to the tune that is playing. Snowball was studied by Aniruddh Patel, senior fellow at the Neurosciences Institute in California and he concluded "Like a child, he synched to the music...Statistically those periods when he's locked onto the beat are not by chance-they really do indicate sensitivity to the beat and an ability to synchronize with tit" Patel says dancing is associated with our vocal abilities, not musical hard wiring. Humans and parrots are two of the few species with brains wired for vocal learning - hearing sounds (like words), then coordinating complex movements (lips, tongues, vocal cords) to reproduce those sounds. Other animals who have this ability: dolphins seals and whales. "In theory," he says, "they may be able to dance, too. We just don't know it yet."
If you enjoyed this, snowball has other videos on YouTube: in a commercial, http://www.youtube.com/watch?v=Gbud5WnNpbI, with Ringo, http://www.youtube.com/watch?v=CqFG4tnX2IE, with Stevie Nicks, http://www.youtube.com/watch?v=GYMBIGTteWA, and a few more.
A book that covers parrots vocal abilites is one of my favorites this year: Alex and Me by Irene Pepperberg.