Yes, the LED blinks when AMBEtest3 runs.
when I run AMBEserver -s 460800 -p 2460 -i /dev/ttyUSB0 I see the LED blink 1 time.

dropping the speed to 230400 doesn't change anything. The thumbDV just arrived here a week ago; I assume it was (is) a new version.

I could try to run the device on a windows machine if that makes sense. Please let me know.
73, John NX2I