He uses fill flash a lot.
What is fill flash, I hear you ask?
Fill flash is when you use your flash to fill in light in the foreground. It can be used when shooting backlit subjects. It can be used to kill ambient light. It can be used to isolate your 'subject' from the background. Fill flash is a very handy tool.
Firstly, you need an off camera flash. You can use your fixed flash, but it lacks the flexibility of an off camera flash. It can only illuminate the foreground of what is in front of the lens.
I picked an old second hand flash up from trademe that works very nicely as a fill flash. It took a bit of fiddling to work out how to make the most of it, I admit. With the use of a $12 slave module that I attach to the bottom of the unit, I can use the camera on command mode, and hand hold the flash to direct it as I want.
As you can imagine, this opens up untold creative possibilities.
By shooting in timer mode, you can move about and direct the flash to deliver light right where you want it. You can kill ambient light, and bring backlight, sidelight, or front light onto your subject. You can light from above or below. Watch this video of Bryan's, you will see what I mean.