Just how funny is Conan O'Brien? Only a few seconds into the March 13 world premiere of Rodman Flender's documentary Conan O'Brien Can't Stop, the South by Southwest festival audience was howling. The love kept on coming with a standing ovation when Flender and O'Brien took the stage afterward for a rousing Q&A. It's no surprise, then, that within 24 hours of the premiere, the film landed a multiplatform distribution deal with Abramorama, Magnolia Home Entertainment, and AT&T's U-verse subscription TV service. The doc follows the disgruntled former Tonight Show host as he channels his anger (''Sometimes I'm so mad I can't even breathe,'' he admits) into last summer's 32-city Legally Prohibited From Being Funny on Television Tour. Throughout the movie, O'Brien is raw, honest, and always hysterical, even when his targets are the members of his devoted staff. He punches a writer repeatedly in the shin; he requires his assistant to talk into a banana phone when she wants to speak. ''After he saw the first cut of the movie,'' Flender tells EW, ''he said, 'I feel like an alcoholic who now has to go apologize to people.'''