According to Deadline, a man passed out during a screening for the found-footage horror film, which is directed by David Bruckner, Glenn McQuaid, Radio Silence, Joe Swanberg, Ti West, and Adam Wingard. This happened early during the film, during a “particularly gruesome scene,” after which the embarrassed man had to leave the theater. He was able to meet the directors later on. Deadline’s report also says another theater-goer was treated for nausea 20 minutes later.
V/H/S is described as a found-footage horror, and it’s possible that the format of the movie, which may include a lot of shaky-camera shots, could have induced the fainting and nausea. Or maybe whatever it was that goes on during the first part of the movie is really that jarring that people are blacking out.