I'm a little late to the party on this one, but I agree with morpheus that trying to say that any specific religious organization or charity should go and help a specific person in a specific situation is a bad place to start a conversation. First, it's pretty trivial to show that this is a poorly reasoned argument. Second, because of the first, it's readily apparent that the argument is being made only to have something to accuse the other party on.
Furthermore, filming anyone in a situation like this is always going to make someone ill at ease. The implication is that the filming is being done because the person with the camera expects something noteworthy to happen. No one tries to catch their conversion on film, so obviously the person with the camera is trying to create a 'gotcha!' moment.
Under the circumstances I can somewhat understand the JWs not wanting to engage too much. I'd be surprised if they'd relocated upon the same questioning (at least from the first video) had he not been filming, but I could be wrong. That said, I think they could also have done a much better job of explaining themselves, especially knowing that failure to do so would likely "bring reproach upon jehovah's name" as the video was destined for youtube. I like his strategy of asking questions, but videoing it isn't going to help these poor kids that are trapped (whether they realize it or not) in the mental prison of the cult.
I guess on some level it's beneficial to make them look silly to the public, but at this point the JW recruiting is completely unproductive so helping members to think instead of feeding their persecution complex is probably the better way to kill this cult. I think following them at the end of the first video was too far and probably killed any chance he had of actually implanting some doubt in the kid's mind.