I have a WD 2TB SATA USB 2.0 drive attached to my WD TV Live Hub. I can see and access the 2 TB USB drive and the WD TV Live Hub 1 TB internal drive on my home network even when the WD TV Live Hub is powered Off. The WD TV Live Hub operates as a NAS drive.
As for seeing or accessing a USB drive attached to the WD TV Live Hub outside my home via WDPhoto app, I believe that only your photo files will be visible and accessible.
