It's nice to see interest in crosspicking technique. I intended to respond earlier but have been busy. Sorry.

The YouTube video clip that M.Ted first linked and that you're all referring to is an excerpt from Clinch Mountain Guitar (DVD, CD and Tab Book) By James Alan Shelton. Shelton currently performs with Ralph Stanley and the Clinch Mountain Boys and is a superb player in this style in his own right. Shelton is the one interviewing Shuffler in the YouTube clip.

There are two main styles of guitar crosspicking in wide use today. The first is the Shuffler-Napier (George and Bill argued over who was first) "DDU" style. The second is the strict "DUDU" style preferred by most modern flatpick virtuosos. Clarence White, an early virtuoso and inspiration for Tony Rice, used both techniques.

The "DDU" style is perfect for those Will You Miss Me When I'm Gone? kind of tunes where blinding speed isn't a requirement. the "DUDU" style, once mastered, will give you more speed for those hot rags and breakdowns.

Each style presents its own challenges to mastery. The "DDU" style forces one to carefully develop muscle memory for the quirky motion needed to play it. The "DUDU" style is easier for the picking hand because the player doesn't need to anticipate an alteration of the usual pick movement in order to do it. But the "DUDU" does force the player to deal with playing strings and beats in different directions depending on where the pattern falls.

One key to Shuffler's playing in the YouTube clip is that he's mostly using "DDU" over and over, not a strict "DDUDDUDU" eight quaver pattern. You'll notice he starts with a crotchet on a down stroke and the next quaver is an up stroke. There is a quaver's rest following the first note but George doesn't depart from the "DDU" pattern, the second note (3rd quaver) is an up stroke.

Try these exercises while holding a partial G chord on the second third and fourth strings (i.e., xx543x bass to treble).

1. "DDU" (a) Play the two measure pattern "DDUDDUDDUDDUDDU-" across those three strings where the last quaver "-" is a rest. Stay on this step until you can do it smoothly (not necessarily quickly) with a metronome. You'll be playing twice as many beats as the metronome.
   
   
2. "DDU" (b) Play the same exercise but every second time you strike the second string drop your pinky onto the 5th fret (i.e., xx545x). No need to lift your index finger from the third fret. Again, work with a metronome.
   
   
3. "DDU" (c) Play (b) as above but after playing the pattern completely one time, change your left hand fingering to a partial D7 chord (i.e., xx453x) by switching strings with your second and third fingers. Play the partial D7 just as you did the partial G adding the E note every second time using your pinky.
   
   
4. "DUDU" If you've mastered the previous exercises but haven't tried this technique before, it's going to feel strange even though you're accustomed to strict DUDU flatpicking. Go through the previous exercises but this time adhere strictly to a DUDU... pick direction. Down strokes are always on odd numbered quavers, up strokes are always on even numbered quavers. If you play a quaver of rest, you'll probably want to move your pick silently above the strings just so your hand doesn't lose the feel of the DUDU... pattern. You will find yourself playing a down stroke on the second (B) string followed by an up stroke on the fourth (D) string and each time you strike a string it will be in a different direction than the last time you struck it.

These exercises are easy to learn but hard to master. By the time you've mastered them, you'll be able to crosspick just about any tune you already know.

You'll have the best results using a heavy pick that doesn't flex when you use it. It should be held vertically or perhaps leaned slightly so the wide end of the pick is slightly ahead of the working end. Also angle it slightly so the edge of your pick that's closest to the fingerboard hits the string first. You may even want to sand and polish a small bevel where the pick strikes the string. Of course you can buy picks with the bevel already there.

To hold the pick, hold your hand out as though you were gripping a vertical post a couple of centimeters in diameter. Place the pick on the side of your index finger so the pick is horizontal and the point of the pick points away at ninety degrees to the surface of your fingernail. Now lay your thumb down on the pick so that the thumb's first joint is at the near edge of the pick and the tip of your thumb extends well beyond the far edge.

Do not hold the pick between the pads of thumb and forefinger. Never mind what George does in the video in this respect.

Do not get a "death grip" on the pick. Hold it naturally so your hand may relax while you play.

Picking motion will come from your wrist, from the flexing of your thumb and forefinger together, and (less so) from your forearm.

Fingers two, three and four of your picking hand should be relaxed and slightly bent. They may lightly touch the surface of your guitar to act as a guide for pick depth but under no circumstances should you "plant" these fingers on the top as a brace for picking.

Do not allow the heel of your picking hand to rest on the bridge or bridge pins.

Good luck. And post back here to let me know how this goes.

      - Mark