It's real. "could be real"? hehe. Yeah, Treadwell did his filming of himself, Herzog came along after his death and put together the movie, did the interviews, voiceover etc. He often encourages the bizarre in his docos, doesn't edit it out, often leaves the camera rolling on an interviewee ages longer than anyone else would - I love that. Uses the least appropriate music imaginable (which often works brilliantly) I know what you mean, they seem very, very odd. It's mainly that every other camera person/director tries to make things/people seem relatively normal, not-weird.

I've seen almost all Herzog's docos, all worth seeing, Grizzly Man is my favourite though. The one about the internet, from a couple of years ago, is one of his best also. Try Fata Morgana for weirdness, or the bleak/beautiful Lessons of Darkness, both set in the desert.