I'm far from an expert on dance, so I'll defer to Fred Astaire, who reportedly called this sequence the greatest dance number ever filmed. The Nicholas Brothers, Fayard and Harold [official site], were most famous for the Hollywood musicals of the 30s and 40s, but their dance careers spanned six decades.
I hate to so shamelessly repost something I saw on Kottke for the second time in a few months, but this dance video is so intoxicating I can't resist. It uses motion capture of some mesmerizing dance performances, and mixes in the artistry of mapping those body movements on to some wild textures and physiologies. The result feels very organic and real, even in cases when the "dancer" couldn't possibly be a living three-dimensional being. Also, the soundtrack by Major Lazer is so infectious that it makes me want to drop whatever I'm doing, go out and run.
See also: one of my favorite videos, for Wide Open by Chemical Brothers, which also mixed motion capture with live performance.
Seventeen years before Kubrick rotated a set to simulate a zero-gee walk in 2001: A Space Odyssey (and decades before Christopher Nolan's monstrous rotating corridor achieved the effect in Inception), Fred Astaire blew audience's minds by dancing up walls and on to the ceiling. Animator Galen Fott created a tweaked view of the scene that allows us to see how it worked.
Astaire sets up the effect with a magician's flair: he performs a few dance moves that almost appear to defy gravity before the room ever rotates. They both foreshadow the effect and desensitize us to it, so when he suddenly transitions to dancing the wall, it's an even more magical moment.
It's also worth reading Fott's description of how he created this view, and his insights into some of the key moments, when you realize just how much effort went into creating this dance number.
I really enjoy this song, and the video is lovely. Judging from some of the comments it receives, it also creeps out people with trypophobia, or a fear or surfaces perforated by lots of holes.
The "making of" version is every bit as captivating. The action is a single shot in a real environment, but the filmmakers mapped on a virtual version of the set so the dancer (or portions of her) could be subtracted and reconstructed as the wire-frame version of her body. I also liked seeing the test versions of what her alternate body might have looked like. I probably would have chosen another option (one had a more organic texture, with branching segments that resembled an arterial system) so it would have been interesting to hear the discussions that led to their decision.