OK, I found out some more info on this and it is for real.....sort of and a trick...sort of.

Here is the deal, he is not just holding his breath for that time as you would think. He prepares for this by doing things a normal person would not do. One of the things he does is sleep in a chamber that simulates the thin air at 15,000 feet. The other thing he does is breath pure oxygen before holding the pure oxygen as his last breath.

I don't know about all of you, but when I am thinking about someone holding their breath in water, I am picturing it as it was when I was a child. You know, three deep breaths, and then hold yourself under the pool ladder while your friend timed you.....LOL.... Hold on Timmy, I have to get out of my chamber....let me put on that oxygen mask........ok ready. I WIN!!!