Hey sarcazmo,
Lot of good flatpicking going on there, if what you're asking about is that strumming pattern he's using. That's all in those pick strokes, and I think he's putting an upstroke in between those notes on the 3rd string. It's not as hard to do, if you slow it down first. First try it using a straight UDUD pattern, you can add that other stroke later.

I'll probably end up goofing around with it next time I grab the Martin. If you want to prep yourself for something like it, or get some basic ideas for this concept. I have a tutorial on Sycopated Strumming Patterns, and it will help you build consistency in your pick strokes.

Here's the link.
http://www.guitartricks.com/tutorial.php?input=995

I've heard this guy before, and he has many influences. Clarence White, Tony Rice, Doc & Merle Watson, even hear some Django. There are many more, but I won't name them all now. We'll just say he's a great picker, and leave it at that.

Are you really interested in bluegrass? Were you looking for bluegrass, or did you just happen to find the video. I was just wondering, because he flatpicks those old fiddle tunes. Anyway, let me know if I can help you with anything.