This is a great movement to use as a warm-up because it activates the nervous system without overly fatiguing the body. It also teaches you to jump with a weight in your hands, as with Olympic-style lifts.
The movement with the legs should be very fast and explosive. Use a powerful hip action.
The arm with the dumbbell should stay close to the body as it rises.
Remember, while you do pull with the arm, it's the movement created by your lower body that gets the dumbbell overhead.
Mike Boyle hates the question, "If you could only do one exercise, what would it be?" To him, it's like asking if Superman could beat the Hulk. Regardless, he gave us an answer that's pretty intriguing.