A weak attempt at provocation that nonetheless puts across a valid point, “Planet of the Arabs” is a pastiche with an attitude. Arab-American filmmaker Jacqueline Salloum assembled clips from assorted TV shows and movies depicting negative Arabic stereotypes. Inspired by a nonfiction book that itemized how thousands of Hollywood products have derided her people while only a handful have treated Arabs fairly, Solloum strings together pieces of “Exodus,” “True Lies,” “Rules of Engagement,” an old Looney Tunes cartoon, an episode of “Law & Order,” and so on. The point is made well enough that most Arabic characters are frothing-at-the-mouth murderers, but that isn’t exactly a bold revelation; the American movie industry has been marginalizing and dehumanizing persons of color since the earliest days of cinema. While Salloum forcefully pursues an admirable agenda, her film is ultimately nothing more than a clip reel because it lacks context and analysis.