In photoshop, I can make out the words, "video" a percentage sign (I think) and at the far right the words "or black" or "of black"
I tried playing with the saturation and gamma on the photo but it's still hard to see. It could be a graphic that someone was working on that mistakenly got punched on air. I do see the word 'black' over the 'LIVE Today' at lower right, and there are definitely other words below the X superimposed over Cheney's quote.
Since this was not live at the time the X aired, the super is appearing over video. I originally thought this could not have been an error, but I see now how it could be after all.
Good work! I think this supports, somehwat, what 'feedback doctor' is saying: probably some control room foul-up.