This trick is very similar to the Three in one hand multiplex pattern in that you effectively juggle Two in one hand by using a Column Multiplex throw. However, in this pattern you make a quick Claw catch of one of the balls in the previous throw so that EVERY throw is a column multiplex. This trick can be pretty tiring for your arm.
Start off with two balls in one hand. Throw the first ball up to just above head height as if you were starting a normal two in one hand rolling out pattern. Then with one arm movement throw the second ball up to eye level (so it is thrown LOWER than the first throw) keep moving your arm upwards & catch the first ball. Hold this ball using the butt of your thumb & your little & ring fingers. Now with your hand higher than the ball in the air, bring it down & Claw the second ball out of the air & bring both balls in the same hand back down to waist height.
Because you are already holding a ball the claw catch needs to be made using only your thumb, fore & middle fingers. When you catch the first ball try & hold it as close to your wrist as possible so that you can use as much of your free fingers as possible. As your hand comes down on the ball spread your fore & middle fingers into a wide 'V' shape & hold your thumb out wide too so that you can grab the ball from three sides. Once caught you can hold the ball against the one already in your hand for an even firmer grip if necessary.
The catches need to be made very quickly, the rhythm you need to aim for is, "throw, throw-catch-claw" (you can't even say it at the speed at which you need to do it).
Now take all three balls in the same hand (take a look at the Three in one hand tutorial for a few ways of holding three balls if you haven't already). Start with a throw of a single ball as before to just above head height. Then throw a column multiplex throw underneath so that the topmost ball peaks at the same height as the first throw. Continue the upward motion of your arm & catch the first ball then claw the lower ball of the stack, just like you practised with two balls. Catch the last ball & stop.
Now do the same again, but don't stop. After clawing the lower ball, snap the balls down & throw another column mutiplex, in the same motion catch the topmost ball of the first multiplex then claw the lower ball of the second stack. After the first throw of the single ball & the first multiplex the pattern is simply a repitition of the catch-claw-multiplex move.
As I said, this pattern can be quite tiring on the arm because. You can reduce the workload by throwing the multiplex so that the balls split as wide as possible. Try to make the top ball rise above your head but keep the lower ball below shoulder height. Then your arm doesn't have to move so far to gather the balls up for the next multiplex throw.