Is it legal for my Crazy neighbor and to video tape from his home?

Is is legal for him to point his video camera into the street to tape activity? It is on a tripod pointed outside of his livingroom window. I'm worried he is using it to zoom in and get a better look of the children in the neighboorhood. He is that psychotic that I wouldn't put it p him. If it's legal to have it though, there isn't much I can do?