Polished and manipulative? Yes. Hoax? No. (SPOILERS)
The first time I watched this was very late at night and I completely bought it. Minutes after it ended, I played right into the hands of the filmmakers and went searching for info about Kristin. Like many posters here, I found it hard to believe that a sleazy porn producer could keep someone's injury or death a secret when "documentary" cameras were capturing every minute. When I stumbled on the YouTube footage of Patrick attacking Kristin and discussions like the one here, I realized I'd been had.
Re-watching key parts of the movie, it's apparent that most of the story was prewritten and staged. The interviews with established industry professionals were genuine and I think most of the pitches for "Virgin Territory" were sincerely made to decision makers knowing it would be rejected. But it seems clear that the principal characters were just that: characters. Considering none of them were professional actors, their performances were great. With no reason to be skeptical, they certainly convinced me!
For me, the giveaway was the unlikely way Kevin Blatt latches onto the guys' allegedly sarcastic throwaway pitch for "Starvation Island". Coupled with the fact that nothing is made of the documentary cameras supposedly capturing an attempted murder in the background, I gotta call shenanigans.
All that said, I don't consider it a hoax and I certainly wasn't upset about "falling for" a fake documentary. The subject is viewers' thirst for reality no matter how unrealistic and in that respect, the makers of "American Cannibal" succeeded brilliantly. Well done.