Well, this is how it works. One of those tricks that is hard to figure out at first, but not too bad once you finally get the hang of it (like loops).
You do split bottom entry, and then a somersault. The somersault is important since it gives momentum to the yo-yo.
Then you do the first underpass of atom smasher. Now as you do that underpass, the yo-yo will hit the string farthest from you. That is when you start the hand motion.
After that first underpass, everything basically stays in the same spot. The yo-yo bounces from that string farthest from you, and the string closest to you.
It is all timing, but it is important that you just don't try to move the yo-yo back and forth like rock the baby.
All of the motion is straight up and down with your yo-yo hand. It is the tightening and slacking of the strings that causes the bounce. The somersault and underpass get the momentum going, and then the motion of your hand keeps it going.
I find it helps if you keep your hands apart so that the string is taut, and then just give slight slack for the up and down motion. You don't want your hands getting really close to each other as you bounce.
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Up there is some goofy ascii drawings. Top one the yo-yo is at one side, second the string is taut, third is at the other side. When you are doing it right, it should feel very smooth. It shouldn't feel like the yo-yo is whacking around. When you pull up, it should push the yo-yo over, and then lower the hand again as it hits the other side again.
Hope that helps...
