GREAT experience and while they technically allow you to take pictures, you cant really see anything with the way it is set up. Honestly I would suggest this, this is what we did and saved like 50% on the excursion.
Book independently, do not go through Disney. That way you get off the ship in port, take a taxi (and there are taxis waiting for you at the port dock that charge $4/person anywhere on the island), and go to the company that is selling the Dolphin experience (forgot the name). They have a large boat/ferry that takes you to the island. After the dolphin experience, there is a ferry from the island that takes you back to the mainland and it drops you off at the save pier as the Disney ship is at!
As to saving money on the pictures, I would just get all the pictures/video on a thumb drive (they sell that). The thumb drive is locked to prevent you copying pictures/video but some basic computer skills can get you past that. Save a ton of money that way.