I think the reasoning is that a big part of your check is the experience, and you would be cheapening the experience by posting it on YouTube. I mean, don't get me wrong, it's still a stupid policy. Pretty much every ride at Disney's on YouTube (how some of them hold those camera's, I have no idea) and it would probably be better for me just to watch T-Rex on video rather than go in there. From what I've heard, it sounds like a torture chamber for autistics.