TV and movies

Why do movies and television captivate our attention? What need is being filled by watching? I can buy into answers involving "escaping everyday realities," "relaxation," "unwinding," etc. from adults (even though I don't quite believe them), but such answers are totally inadequate for children. In my experience, TV/film does exactly the opposite for children: winds them up, makes them less relaxed, and makes them think that "everyday realities" include car chases, deaths, gunfights, flying people, cliff-hanging and a hundred other varieties of peril.