I don't think it's feasible for someone to maintain that level of genuine anger throughout the stop-start logistical process of filming a DVD. Either he's genuinely mentally ill and everyone else involved in the production was complicit in exploiting him, or, which is more likely, he was well aware of what he was doing and it was a deliberate presentational ploy. I refer you to Jerry Sadowitz, Bill Hicks, Doug Stanhope, Stewart Lee, and many other performers who've made similar choices. Yeah, it's not likely to appeal to everyone, but I thought it was obviously a character and I found it funny.