They were kind of ambiguous about it. The first announcement said that you couldn't use video lights or take flash pictures. The second announcement said that you couldn't record video or take pictures. I suspect that the second announcement was a holdover from the old rules. I was really obvious with my picture taking and no one ever said a thing.
It's pretty easy getting good Nemo pictures. Spend a lot of money on a big, heavy, expensive camera and a big, heavy expensive lens. Drag them all over the Animal Kingdom. Take a bunch of pictures of the Nemo show with them and keep the few that come out OK.
Alternatively, just find someone that got decent shots and use theirs.