Mark first outlines the importance of a split step.  Most pros will agree that the split step is essential for quick reaction time and first movement towards the ball.  Having your feet shoulder width apart allows for balance and early preparation.

Next, Mark outlines racquet placement (out in front just below the eyes), first step, and meeting the ball out in front. 

I happen to be a big fan of this video - It's simple, to the point, and TRUE!