When Tom DiCillo made the arch Johnny Suede, his lead actor was little known. Now Brad Pitt is a sensation, and DiCillo, well, isn’t. Perhaps that’s why the director’s new effort is titled Living in Oblivion and concerns an ill-fated film shoot. Steve Buscemi stars in this flick, which has been described as the best in the recent outbreak of low-budget films about low-budget filmmaking. Today and tomorrow at 8 p.m. (the director will introduce the latter screening) at the Hirshhorn Museum and Sculpture Garden’s Ring Auditorium, 7th St. & Independence Ave. SW. FREE. (202) 357-2700. (Mark Jenkins)