Oh we had this problem today! Normally dd saves her scary stuff for after he's gone to bed, and has to put up with Cars or CBeebies. Today we were in all afternoon so we put the laptop in her room and she watched up there while ds played downstairs.
It would be tricky if she was watching downstairs. Unless I was with ds the whole time playing in his room, I don't think I could keep him out of the living room.