A film that tries to be a serious documentary, but is evidenced-challenged, i.e. based on crack-pot journalism, so that it doesn't quite qualify as a regular documentary. This is distinct from a mockumentary/Michael Moore film, in that it carries a serious tone thoughout, and does not try to be funny. e.g. Loose Change, and most other 9/11 conspiracy films.
Frank: "Hey, did you hear about that movie, Zeitgeist?"
Charlie: "What kind of movie is it?"
Frank: "It's kind of a documentary, about how the Federal Reserve starts wars to further it's goal of one world government."
Charlie: "Umm, that sounds more like a crack-potumentary to me, pal. You might want to check your sources..."