Guessing it was this video you watched?
On the topic of the display pulsing/flickering, my guess is that this may be an effect that is really only evident in videos rather than seeing it in person, I suspect that the refresh rate of the VFD is different to the frame rate of the video recording and hence you see a flickering effect when viewed through the camera. I could be totally wrong of course, I've just asked the question of the owner in that video, awaiting a reply.
I had some type of submarine/battleship style game back in the 80's that had what was probably a VFD display and I don't really recall it flickering very much.
That being said, I really like the pulsating effect even if it does prove to not be totally accurate.