I believe it was done intentionally, but I don't think the graphic overlay was created specifically for the job. Instead, I think someone mucked around with a piece of equipment knowing that it would generate the black "X". This gives them plausible deniability after the fact.
That is, the black "X" image is probably some valid output of the device, indicating lack of signal or whatever, and the technician knew it could be made to do this. So he tweaked it a few times during the speech. When caught, he easily plays the "mistake" card.
In non-linear editing, an X is often imposed over a video transition that has not been rendered yet.