The FT230X uses the default FTDI VID/PID, so it should be recognized with Windows Update.  If you don't have an Internet connection, or see the device under the "Other" devices tree in Device Manager, then run their EXE installer:

Unplug the ThumbDV, run the EXE, then plug the ThumbDV back in.  If you still have troubles after running the EXE, try right-clicking on the ThumbDV in the Device Manager, then select "Update Drivers"