I'm not sure if you can call this flickering, but the HID beam moves a little. It does it with the engine off and running. If you stare at the bulb it doesn't seem to flicker, but the beam does.
I've asked and searched around and it seems that the common solution is to use either relays and/or capacitors but it also seems to be not too effective.
Has anyone seen and fixed something like this?
HID flicker - YouTube