I don't think the system works like that.
From my first quick take of the video, the app+turnstyle is used to identify you to the store. The video system then tracks your position as you walk around.
When you walk out, the items are recognized and tallied by a large RFID sweep. Funneling you back out through a turnstyle makes sure the vision system knows it's you. Notice that you don't need to barcode yourself on the way out, and the exit system is phone agnostic (it's not checking for an NFC or Apple Pay tag or anything).
The whole "tracking individual items as they come on and off the shelves" task is a very complex thing. But tracking bodies as they walk around a 1,500 square foot room isn't that hard.