There are dozens of impressive YouTube videos of this gifted young cellist. He is also a very talented pianist.
Also, take a moment to watch this video of his mother, who has a parenting website at http://www.NaomiAldort.com. What she's saying might sound surprising, but her point is good. In order to help a child change unacceptable behavior, we need to acknowledge the feelings that have led to that behavior. Often the problems that parents run into while practicing have less to do with the actual technical and physical challenges of playing music, and more to do with the child's emotional life.