The camera will scan a printed barcode.
That vid showed a phone camera pointed at someone’s unmarked arm, then the phone moved to the right of the view, at which time the barcode displayed.
I wasn’t there. But I have personally seen a magnet stick to the arm (at injection site of a freshly “vaccinated” person with Moderna. I also saw something under the surface of the skin poking up and moving around with the magnet. Can you explain that?