Oh, look, a legitimately clever use of the iPhone, and one that’s not hard at all to replicate at home. Essentially, you set your iPhone on a raised surface, then you snap away using the phone’s camera. Congratulations, you’ve just created an inexpensive document scanner.
The key here, obviously, and why this is more effective than merely holding a sheet of paper up to the phone’s camera is that the document is always a fixed distance away. Plus, both the phone and document are stationary, ensuring that your “scan” won’t be unreadably blurry.
Of course, you could opt out of all cutting cardboard and whatnot by paying $45 for it.