Hmmmmm....it shows the iPhone in the video (on the screen of the Mac using the iSight), but looks a little fishy to me. Could've been a "normal" phone with a piece of paper stuck to the back printed to make it look like the back of the iPhone.
Also, I think I saw some customers in that Apple Store. I highly doubt they'd let any employee take an iPhone and walk around the store with it while the store is open.
Oh, and I just heard the audio. Someone on that page commented that the dude who says "Hey! What are you doing?" is obviously put in there after the video was taken. The quality of the sound it too good compared to the rest of the audio.