On the other hand, I find it somewhat ridiculous that you would not object to showing whatever it is you're showing, in public, to a handful of strangers, but you would suddenly object if it was shown, over the Internet, to a few more strangers.
I don't know what the law should be -- it always bothered me when some video shown on TV has various faces blurred out, because they never got that person to sign some sort of waiver. On the other hand, if you're going to snap a photo of someone, and then turn that into an international ad campaign, I'd argue you should have to get their consent, and probably pay them for the privilege.
But regardless of what the law should be, common sense now dictates that if you are in public, you should assume that anything you do might be photographed and broadcast. It's like sex tapes -- sure it was just for the boyfriend, but why do that unless you either wanted it public, or knew the guy well enough to trust him with that? Or piracy -- I won't defend copyright infringement, but assume that very smart people will succeed in pirating your stuff and sharing it with the world, and build your business model with that in mind.