I have the same service through Cox and it is my understanding that the USB port that you see does nothing right now from what Cox says, Comcast might be different and have the USB working. But for right now, there is only two ways to get more space on your dvr. 1. Erase the tv shows that you have already watched and don't want to save. 2. Transfer your tv shows to a VHS video tape or dvd disc. For the vcr just follow instructions that your local cable company should have for hooking up the dvr and vcr together.