Jen Chandler does an awesome job of demoing two of the best movements for flexibility, stability, and they just down right look cool. Watch Jen use 8kg Kettlebell to practice the High Windmill and Two Handed Anyhow.
These movements are to be performed with very strict form and very slowly in order to achieve the desired results of flexility, strength stability, and core strength development. Pay close attention to her locked legs and locked out elbow. Both are vital for completing these movements well.