Global Reef is making a documentary of the dive and is currently raising funds for the project. You can find out more by watching the video below then clicking here to read up on Scott and why he is doing this. You'll also be able to donate from that same page.
Staying submerged underwater and swimming for that long is going to be insanely tough. I can't imagine who tired you would be after just a few hours under the water. I have no idea if he plans to surface to change out his oxygen bottles or if they've come up with something different to address that issue. Either way, it's going to be one very difficult day in the water.