Same experience here.
-XP with Gizmo 4.0 v325 and a Logitech QuickCam UltraVision
-N800 OS2008 with Gizmo 4.0.0 (build 95)

If the PC initiates the call, the PC's Gizmo reports that it can't start video.
If the N800 initiates the call, both clients see their own video, but neither one sees the other. Audio is being transmitted.