Anyway, it's a documentary about how the MPAA ratings board works, and who makes the decisions about what movies you get to see (since an NC-17 rating is the kiss of death to distribution and to advertising budgets). The MPAA is very secretive about this: they're the gatekeepers of a huge part of our culture, and we don't get to know who they are or how they make their decisions. So the filmmakers hired a private detective to figure out who these people are. That part is very entertaining. The best part, though, is the side-by-side comparisons of what gets an R and what gets an NC-17. Hint: they don't like women who enjoy sex, or gays.
The MPAA, of course, gave it an NC-17. How could they resist?
Watch the DVD bonus material too, it's also good.