From Youtube:
“The Exorcist” director William Friedkin terrified the Venice Film Festival last year with his new documentary, “The Devil and Father Amorth,” and now everyone can see why in the official trailer. The non-fiction feature profiles the late Father Gabriele Amortha as he performs his ninth exorcism on an Italian woman. Friedkin was in the room for the exorcism, and it shook him to his core.
“It was terrifying,” Friedkin told Variety at the Venice Film Festival about recording the footage. “I went from being afraid of what could happen to feeling a great deal of empathy with this woman’s pain and suffering, which is obvious in the film.”