How do I know who scans my QR Codes?
If someone simply scans a code that points to a general URL (i.e. a video, a corporate website, landing page), you do not know who they are. You must drive them to a landing page where they could enter their information, and thus be added to your marketing database.
However, if you generated a QR Code for a Personalized URL, you would be able to tell who scanned the code, simply by the scan.