Matt Johnson's tragicomic video-cam portrait of two high-school misfits whose creative energies turn to post-Columbine anger is a more interesting proposition than it is a finished film. Playing with (but never quite mastering) the layers of meta-textuality involved in shooting an undercover feature while posing as students working on a homemade "revenge movie", The Dirties veers uneasily between provocative insight, snarky cine-literate humour and plain hokey contrivance, never quite finding its faux vérité register. The subject of bullying is convincingly depicted, and there's an attempt to grapple with the transition from class clown to killer, but this lacks the depth, emotional clout and (oddly enough) empathy of Gus Van Sant's altogether superior Elephant.