It can hardly be called a documentary. Combine a story-less series of activities with a budget-less production and a crew with a single camera (which is used throughout the movie as the lens) and you get paranormal activity. First things first, there's nothing paranormal about this movie. There's a plump girl who gets aroused during nights because her boyfriend is busy all the time with his camera, something he carries everywhere he goes. Even when she's screaming, he grabs the camera first before rushing downstairs. The entire movie is shown through the lens of the camera and believe me this is high on the list of how a movie should NOT be made. You don't want to keep watching through a jerky camera for more than a few minutes, leave alone an entire movie. The scariest thing that happens in this movie is that the girl throws the guy away a few feet. That's it. I wasn't even amused.
The boyfriend supposedly wants to help but just ends up fighting because the girl wants him to give up the camera. He does not. The guy takes his camera everywhere -- to the toilet, to the dining table, to the bedroom. I mean everywhere. He's recording even when they have supposedly serious conversation about tackling the situation. And lord even when playing back the recorded movies on his laptop.
Did you note that I did not mention about ghosts or anything paranormal above? That's because there isn't any. Save yourself the time and go blackmail a bandit if you want to make better use of your time.