In his own special dialect, CrossFit kettlebell expert Jeff Martone takes athletes at a Kettlebell Cert through a top-down progression as they learn the kettlebell thruster. Working through the press, and front squat/push press, Martone explains core-to-extremity movement is critical to success.
The key to the kettlebell thruster is keeping your elbows tight against your body, allowing the momentum created by explosive hip extension to be transferred efficiently to the bells. After the kettlebells start to rise due to hip extension, the pressing phase finishes off the thruster.
At the top, athletes should guard against any rotation of the kettlebell, which adds unnecessary movement to the lift.
Video by Again Faster.
Additional reading: The Kettlebell Press by Jeff Martone, published Oct. 1, 2007.