first off are the sony robots doing a "fan dance". they're so smooth its creepy.
next is an older video put out by Apple about its idea of the future "Knowledge Navigator." this idea of a personal assistant was presented in the past as the ultimate in personal computing, but as this article points out, it can only be just that, the ultimate.
it will never work in the interim because as these avatars act more and more human, we expect more and more out of them. when they do not deliver, we quickly abandon them. thus, the only avatar that would ever succeed would be a perfect one. while the idea of avatars might appeal as the ideal HCI (Human-Computer Interaction) device, i doubt it will ever arrive without the ability to evolve.