TELECOM Digest Editor noted in response to Lisa Hancock:
Well, it's easy to hide a webcam by merely throwing a sock over it or putting it in a discrete corner of the desk. As to performing for the webcam, look at it this way: When a boy reaches around 13, he'll start to take up "private time" in his bedroom or bathroom. Presumably the mother is aware of this biological need and will respect his privacy. If she happens to walk in on him she'll discover him doing what other boys do in private, but she shouldn't necessarily realize he's doing it for the webcam. Years ago this practice was discouraged by parents, but not now.
The TV show "Roseanne" did an episode about their son going through that phase and had a scene where the father was awkwardly trying to explain the need for discreteness to the son.