I think it is likely the Aspergers/Autism Spectrum Disorders (ASD). Tigger was like that at 7 but is much better at 12. Since your daughter is older, develop a plan for when this happens. Have her pause her show and very calmly tell him that "we don't hit". Ask her to physically move out of the way to give you time and space to get in between them. If he hits someone, he needs to go to a calming place until he is under control. If he is so out of control that he can't go there, then make wherever he is the calming place by eliminating distractions. It is key (as much as possible) to not let him get whatever it was he wanted that started the outburst. So, in this case, no tv that night.
I think you signature is out of date...it says your difficult child is 4???? Is he on any medications?
