Here's an excellent power training/weights/kettlebell video taken at The National Ballet of Canada, with trainer Josh Hewitt.
Josh introduces an overview of the basics of training for power. He recommends this type of training as useful for men in ballet and shows how it helps explosive movements and partner work.
His demo includes:
-importance of training for power
-exercise progressions for power movements
-other power movements such as plyo pushups and jump squats
These training exercises are meant for advanced/professional dancers and they should not be practiced without instruction and supervision.