When are movies not art or entertainment, but something else entirely—an atrocity exhibition, or rubbernecking masochism? All manner of speculation about the true allure of exploitation psychotronica arises when you confront Ruggero Deodato’s Cannibal Holocaust (1980), an experience preceded, and often overshadowed, by its own drooling reputation. Perhaps the most extreme tissue sample of the dare-you-to-look “mondo” genre that emerged in the ’60s, the movie spends most of its padded time trailing after a news documentarian journeying to the Amazon in search of a lost news crew. The footage he brings back is Deodato’s punchline: A progenitor to The Blair Witch Project, the supposedly raw film “captures” the mega-imperialistic-scumbag film team as it hunts for cannibals, and then finds some. Though hardly as convincing or purely formal as Blair Witch (the images, cuts, and sound have no reliable provenance), Deodato’s film taps into the same primeval element of cinematic dread, in which the frame itself is a source of uneasiness, and even a questionable modicum of nonfiction integrity can flip your stomach. Of course, Deodato is a monster, mercilessly exploiting the natives, butchering virtually every animal in his path (on film), and rubbing our noses in entrails. Still, the savage climax is, given the barbarous behavior of the white protagonists, something of a happy ending. The high-handed gore specialists at Grindhouse have prefaced the movie with a disclaimer, hilariously suggesting it should be viewed as a “document of a bygone era of extreme irresponsibility”—and then they lavishly supplement it with a second disc of commentaries, a one-hour Italian making-of doc, interviews, trailers, art, music videos, and the entire shooting script. However you package it, it’s a bad time.