How it was made:

"The big shot, the one that follows the ball out [from the plate to left field], was completely choreographed for lack of a better word," Smith said, explaining that a motion control shot followed what would have been the trajectory of the ball, and the artisans at New York's Framestore CFC later inserted a ball in post.

As for how the ball girl (played by stuntwoman Phoenix Brown) made the spectacular catch that is the highlight of the video, she got a little help from rigs and Framestore CFC.

Smith and his crew shot the big catch right after the game they were shooting concluded, attaching the ball girl to wires and having two stunt men off to the side literally yanking her up the wall. Read more at http://www.snopes.com/photos/advertisements/ballgirl.asp#UcCFmmR1XqFJhdKx.99

Haha, that's awesome. I wouldn't have known it was fake if you didn't tell me!