There's only one way to ensure a movie will bomb. (Well, okay, two ways, but only Hitler—no, wait, an evil alien Hitler—would be malevolent enough to call Carrot Top and propose Chairman of the Board 2.) Once a film gets rated NC-17, the thing's pretty much DOA: Most theaters won't show it, most video stores won't carry it, and most people won't be able to watch it.

So who determines what ratings films receive—and thus decides what films get shown? The Motion Picture Association of America (MPAA) does, and it turns out they're dicks. A list of arbitrary rules determines which films get what ratings, and a panel of anonymous parents determine whether a film's a G, PG, PG-13, R, or NC-17. With its stranglehold on Hollywood and theaters, the MPAA's process is so influential—yet so secretive—that it's the perfect subject for a documentary.

Half of Not Yet Rated is great. Director Kirby Dick speaks with a fraction of the filmmakers who've been screwed by the system— everyone from Requiem for a Dream's Darren Aronofsky to South Park's Matt Stone—and it's here that the movie has something to say: That the MPAA's ratings system amounts to censorship. Major studios get tips on what to cut in order to achieve the rating they want, while indies receive useless, undetailed rulings. Films with gay sex scenes get slapped with NC-17s, while "straight" films with identical shots get Rs. It's dark, creepy stuff, and how strongly it impacts our culture makes it even more so.

Alas, Dick insists on throwing himself—and his film—into the MPAA clusterfuck, even going so far as to hire a clueless "private eye" to track down the anonymous raters. Dick also uses plenty of goofy, unnecessary animations, and his conversations with MPAA ringleaders are more self-indulgent than revealing. But when actual filmmakers are talking, Not Yet Rated makes a powerful, disturbing point—that the ratings system is flawed, outdated, and distressingly influential. Not Yet Rated will change the way you watch and think of films—unfortunately, it'll also make you wish it was a better movie.