If you try to throw a table tennis ball into a cup one meter away, as this robot is doing, you'll gain a greater appreciation of this little machine. Using three servos in coordinated motion, when properly adjusted this robot can hit the target 9 times out of 10.
And, when not properly tuned, the robot may throw the ball in all directions -- backward, straight up, straight down in front, just dropped in back -- in a way reminiscent of the throws a child makes when first learning the skill.
The cup is plastic, and has some loose coins at the bottom to weight it and also to help absorb energy as the ball hits -- otherwise the ball tends to bounce out easily. A ceramic mug will not work well for the same reason: It is so hard that the ball, even when thrown well, will very often bounce right out again.