I don't think that's entirely correct, at least in the United States. As far as I understand the law, it IS legal to videorecord people, children and otherwise in public places with or without their permission and on private property under some conditions. I'm certainly not a legal expert and I would be interested in seeing any citations that might prove this wrong. Here are a few sources I found on the web:
http://communications-media.lawyers.com/privacy-law/Child-Ph... (note that according to this, in the state of Georgia and possibly New Jersey it may now be illegal to photograph children who aren't your own)