Rolling balls that collide!

So yesterday sitting in robotics, as I was trying to think of something to write my physics blog about, I caught sight of the little green balls that we have to use in the VEX game. Basically, we have to build a robot to get them to the other side of the wall as the opposing robot is dumping the balls on our side of the wall.

Naturally, the first thing I thought of (since I had just been working on Physics homework -_-) was momentum. Let's pretend that there aren't any friction forces, and that the balls are moving in 2 dimensions... despite my efforts I couldn't get the balls to collide and move perfectly in opposite directions.
The moving ball, the one that comes from the left, has momentum that equals it's velocity times it's mass. We'lll assume that the second ball, the one that starts in the middle of the screen, starts from rest (yes, I do realize that it appears to be rolling slightly, but we can pretend it's not for the sake of making this easier) since it has zero velocity.
After the balls collide, there is a change in momentum - the momentum of the ball from the left decreases, and the other ball's momentum increases. In other words, both balls have an impulse value, and the energy is transferred between the balls. According to conservation of momentum, the total momentums of the balls at the beginning and end of the video will be the same. This means that all the momentum that the first moving ball lost was transferred to the other ball.
Since we are assuming that this is a frictionless environment, we can assume that this is an elastic collision - hence, the total kinetic energy stays constant.