The “controversial” video—controversial because it was done in an AT&T store on an iPhone 5 on display—shows an iPhone 5 being rubbed hard against a sharp corner of a plastic display case. The iPhone 5 comes away unscathed, even when the test is repeated several times. It likewise survives the sharp digging and scratching of a fingernail.
The video seems to indicate that, at least when it comes to plastic or acrylics with sharp edges, the back of the iPhone 5 isn’t quite as brittle or easily scratched as another recent popular scratch-test video from iFixIt indicated. That particular test involved metal-on-metal contact.
Some members of the MacRumors forum and commenters on YouTube objected to the methods of the test, pointing out that the creator of the video could have been arrested for attempting to destroy store property. However, no damage was apparently done to the device.