Admit it: dirty movies have a bad reputation. But like any other cultural phenomenon, porn flicks also have a complex history that situates them inside contemporary society (and its dark erotic impulses). Susie Bright, a lecturer with a flair for the sublime and the ridiculous, has the sly ability for placing smut within a telling context, so that it becomes not just filthy pictures, but filthy pictures with meaning. This is no mean skill, and Ms. Bright has made a career of it. As publisher of "On Our Backs," the erotic lesbian magazine, and video reviewer for "Penthouse Forum," she has that rare vantage for seeing beyond the porn industry's crass commercialism to its more revealing gender orientation, taboo tampering and strangely conservative politics. The videoclips that accompany Ms. Bright's lecture cover the entire gamut of sexual activity-straight, gay, and lesbian, with every discrete kink included. However, "How to Read a Dirty Movie" doesn't promote the monotony of grunt-and-grind porn; rather it looks for those transgressive moments that somehow rise above the bedsheets to become revelations about sexuality. It is here that Ms. Bright shines: by pulling the covers off the orthodoxies of porn, we begin to see our own sexual preconceptions emerge, egregious misnomers and all. Deciphering images from the edge of acceptable behavior, Susie Bright can tell you a lot about yourself. Steve Seid Warning: The videoclips presented as part of this evening's lecture contain graphic representations of sexual acts which some people may find offensive.