The subject matter of Rize may be familiar to some as the target of a famous South Park parody, or as the central activity in You Got Served, the failed fiction-film treatment of competitive urban dancing (which that classic South Park episode also skewers). But only in the documentary format -- where the moves aren't, nor could they possibly be, choreographed -- can a viewer truly appreciate the whiplash bursts of adrenaline known as krumping. Even those who think they understand the scene may not be aware that this electric form originated, more or less, with a man in clown makeup. Rize not only explains that apparent paradox, but goes far deeper into the surrounding Los Angeles youth culture -- chosen by many as an alternative to gang violence -- than it might need to. Why wouldn't it need to? Because the phenomenon David LaChapelle's film captures is so vibrant, so unpredictable, and so enthrallingly watchable, it would work almost as well with no narrative spine at all. The fascination of watching body parts flail -- in all their incomprehensible, improvisational brilliance -- never dwindles. It is, however, somewhat disappointing that the film closes with a Hollywood-style climax, a dance-off known as Tommy the Clown's Battle Zone. The essence of clowning and krumping is that they channel the emotional landscape of an individual dancer, making them too subjective to be compared qualitatively, and it's often difficult to determine why one side is awarded victory over the other, except for the relative boisterousness of the crowd. Most of this film's viewers won't have that problem, wanting to cheer all the participants in Rize with equal vigor. Not only are they genius performers, but they stand triumphant over other life choices that operate perilously close to their arena.