Gebhardt founded and directed the University of Cincinnati Film Society in 1970 when Jonas Mekas, a filmmaker whose work the society had featured, asked him to come to New York and manage Anthology Film Archives, his new center devoted to avant-garde cinema. In New York, John Lennon and Ms. Ono hired him to work for Joko Films, their production company. Their collaborations over the next three years included "Fly," which showed, in extreme close-up, a fly (and its many doubles) slowly wandering over a nude woman, and "Up Your Legs Forever," a series of panning shots of 367 human legs.