Having never heard of Chris Perkins until spotting this thread yesterday, I looked him up on youtube and watched most of a video where he was DM'ing at a convention of some sort. I would have finished it, but I had to get to sleep for work today.
While I did find the video highly entertaining, and quite funny in parts, I thought some of the players went a bit overboard with the sex jokes, but he seemed to encourage it a bit...so I guess it was all part of the show.
I don't know the people who were playing, perhaps they are celebrities (or gaming celebrities/writers/editors/designers/etc), but I must admit that I really enjoyed watching them play, something I went in thinking may be quite tedious to sit through. Quite the opposite proved to be true.
He seemed to be cool with letting players do whatever idea they came up with on the spot. Usually had them roll a "check" of some sort to see what the results would be. Some of the failing rolls had funny outcomes as well. I thnk that just comes form DM experience, and can imagine that most well versed DMs should be able to come up with stuff on the fly like that. I think it's a matter of being fair and coming up with something that seems plausable within the context of the game.
Count me as one who enjoyed his roleplaying of the NPC characters, I felt it really added to the game quite a bit, and makes me (maybe) want to try it myself when I start DM'ing for my group.
Being new to the hobby, I am unable to give any meaningful assessment of his skill as a DM, but I can say that I will be watching more of his videos.