A TIME-HONORED tradition: Stand outside a movie theater with a camera and microphone and poll the audience members for their reactions. What did you think of the film? A grandmotherly woman makes a face and waves her hand in disgust: Revolting! Idiotic! A middle-aged gentleman, stout and respectable, takes a more tolerant view: This is a movie about how young people live today, he says, a movie made by young people, and he is generally in favor of young people. But a sober-looking, well-dressed younger fellow demurs. “I don’t think it’s very serious,” he says dismissively.This little scene of impromptu amateur film criticism — or market…