Much of Orson Welles’ last completed film, the head-spinning documentary ”film essay” F for Fake, feels as ahead of its time as did his debut, Citizen Kane. Blasting off with interview footage of art forger Elmyr de Hory and his con-man biographer Clifford Irving (who later, amazingly, forged Howard Hughes’ autobiography), Welles splices together a nonlinear meditation on fraud with a jump-cut, call-and-response style that predates MTV and other imitators. Fake is madcap and confusing, even maddening, but unforgettable, too — particularly the magnificent sequence about the French cathedral Chartres, and whenever Welles himself stomps around in a black hat and magician’s cape. EXTRAS Before the movie, watch the 60 Minutes II interview from 2000 with Irving, a fascinating rascal, and the straight doc on Elmyr. Don’t watch the 90-minute doc on Welles’ unfinished projects till after: It spoils a key Fake surprise.