I found the following manual, but I'm not sure how applicable it is to your model:
http://www.free-instruction-manuals.com ... 042231.pdfThe manual states that recording to a USB mass storage device is disabled (because USB does not have the bandwidth to record multiple video streams), but backing up existing recordings to USB is still possible. If the unit has an eSATA port, then full record/playback is possible via this route.
If there is a LAN port, then it should be possible to retrieve recordings over the network using the supplied "My DVR" application.