See this movie: "This Film Is Not Yet Rated"
It's an expose on the secret MPAA ratings board, with some detours to talk about the power that the MPAA wields in Washington through their lobbists. There's a number of interviews with directors about the trouble they've had with the board and how it is virtually impossible to challenge a rating. Indie directors especially get the shaft, because the system favors the big studios.
The film is dead serious, but often hilarious -- especially when director Kirby Dick sends in This Film Is Not Yet Rated...to be rated.
Watch the DVD extras, too. There's some really funny war stories from directors about sending in their movies to be rated, an interview with the EFF's Fred von Lohmann about the MPAA and their influence on Washington, and the whole story about the MPAA -- scourge of pirates -- making an unauthorized copy of the film (even after Kirby Dick explicity sought an assurance that this would not be done).