I've written about this incredible race before, but this footage shows in more detail some of what was going on during the race. Although the Australians were doing well at the beginning, by the last lap it boils down to the French and the Americans. America's Lezak takes 29 strokes on the way out, versus France's Bernard Alain, who takes 32. Not much difference, although it is already interesting that the taller Frenchman is taking more strokes.
On the way back, things change. Lezak takes 34 strokes, and Alain takes 42. Something happened to Bernard's stroke on the way back, something that didn't happen to Lezak.
Looking at this video again, it's clear that Jason has a very different stroke than Bernard. Maybe it's because he breathes only to his right, and does so on every stroke. But I think there is more going on than that. From the top camera, watch Jason's head. It's going up and down a lot more than Bernard's. Watch his back. His back is pumping up and down more than Bernard's as well. From the underwater camera you can see that Jason is pumping the left side of his body up and down. Bernard goes straight through the water, which looks more efficient, but I don't think efficiency is what is going on here. I think Jason is pumping water backward with his whole torso, like in the butterfly.
One other note: Jason is blowing so much air under his body that his left hand is travelling through that air. Grabbing air cannot be helping propulsion, but it's possible that by getting that air under his body he is reducing his drag.
I'm pretty sure Jason Lezak has found a better way to swim the freestyle.