Chinese taming bears

This video is incredible, i can't understand how they can tame the bears and learn this kind of stuff.
Some years ago, i saw another incredible bears video from 5th Cirque du Montecarlo.
Another bears juggle hulahoop, but there was on of this really impressive. Bear doing backflip with a bit help of human, trick with acrobatic bar and jumping horses (im not sure the translation) and then after this to kick a clown ass!