Photographer David LaChapelle extends his own 2004 short film, Krumped, with this feature-length look into the dance phenomenon of clown/krump, which you can find in most hip-hop videos near you. First witnessed by LaChapelle on the set of Christina Aguilera’s “Drrty” video, he traced the dance back to its origins in South Central LA, where kids have been dancing in the style — a frenetic combination of breakdancing, booty-shaking and something undefinable that could be described as fighting without an opponent — since 1992. It culminates in a big-time battle between the clowners and the krumpers. With so many subjects — though the director focuses on clown founder Tommy the Clown, he also weaves in stories of more than a dozen others — the doc doesn’t go as deep as it could, but as a snapshot of a facet of hip-hop and pop culture, it’s perfect, and devoid of the garish style of LaChapelle’s photographs. Extras are meh — though “Dragon makes lasagna” is a compelling, if bizarre, vignette — but you can learn some krump moves. Like Rize itself, it’s best when you stick to dancing.