Pendulum drops are a very visual trick that are based on the two ball fountain. It's also asymmetrical, so be sure to practice this trick going both directions.
To learn more about pendulums, visit the wikipedia page.
(Sorry about the weird audio in the background--the TV was apparently louder than I thought.)
It can be helpful to remember that the pendulum motion should be two beats long. One beat to catch and swing away from your body, and another beat to swing back in and release it. Try counting the two beats aloud if you're struggling with the timing.