Hm. It turns your TV-which-supports-PVR-functionality into a PVR, AFAICT - and as such I'm not sure how it differs from any other hard drive (other than supporting USB3.0 and coming with a little cradle that fits on the back of your TV).
It probably means its using one of their CE/AV drives (as used in PVRs) that are quieter, produce less heat, draw less power and do less error correction than standard drives