I used Wiki for that. For instance searched "January 13" then F3'd and had my computer highlight "2004." Each time, with each date, I either came across nothing or something insignificant such as some nobody's birth or death. Searched the full dates on Google, no better results. Even looked up newspaper archives, ended up with nothing still.

I'm wondering if it's that the only date which mattered was September 11 2001. So you end up with Moon Landing, Obama Elected, Pearl Harbor, 9/11. Also figured they could be important dates but which the significance of them isn't commonly known or easily determined. Or perhaps History Channel was just being lazy, filling those few seconds with a glob of irrelevant dates knowing that nobody could even read them fast enough anyway - but if so, why 9/11? Other than that, I figured there may be a pattern there but if there is, it isn't clear.