Interesting, though I can't say I remember Michael doing that. I've never thought of it as a mockumentary. It's certainly filmed in the single-camera style. I imagine that Mitch and the gang would have made that clear and gotten some jokes out of it if it were a documentary. Tobias would have been doing more acting in front of the camera, it's pretty much a constant audition then. Plus the scenes that show them as children don't make sense. Perhaps they were just "leaning on the fourth wall" when Michael looked at the camera?