Based on the video, it looks like you use the Amazon app to identify yourself at the turnstile when you enter (via NFC?). The 'supported phones' bit seems to re

Based on the video, it looks like you use the Amazon app to identify yourself at the turnstile when you enter (via NFC?). The 'supported phones' bit seems to refer to phones that can run the Amazon app. Once you're identified, the cameras in the store can associate your image with the Amazon account that was presented and track you around the store. Each item that you grab is added to your virtual cart (unclear if this step is pure computer vision). The act of walking out causes you to be billed for items placed in your cart -- the cameras know you walked up to a turnstile, which activated. I don't believe the phone itself is used after you first enter the store, which eliminates a whole host of potential problems: app crashes, battery dying, losing service, etc. That's my take, anyway.