Linda Ellerbee, for decades, has been turning out clear, crisp, important television on an endless array of topics – sometimes for adults, and, for quite a long time now, for kids. That doesn’t mean she and her producers (in this case, Martin Toub) pander or simplify. Take tonight’s new Nick News special, for example: It interviews kids who have lived through periods when their parents were physically abusing one another. Sometimes, and this is one of those times, just broaching the subject is an important and brave act of TV broadcasting.