>>>The 'X' over Cheney's face appeared each time less than a second, creating an odd subliminal effect.
Technically not subliminal. A subliminal message is a signal or message designed to pass below the normal limits of perception. For example it might be inaudible to the conscious mind (but audible to the unconscious or deeper mind) or might be an image transmitted briefly and unperceived consciously and yet perceived unconsciously.
This would pass way below the normal limit of perception of most demonrats... they are not the brightest bulbs..