I keep changing my mind over how much I think Elizabeth would understand if she'd not been distracted, though. :)

That's a good question. Well, first of all, she herself says she doesn't understand what he's saying. And the fact that she's distracted also shows she's not realizing this is VERY IMPORTANT.

With all due respect to Reagan and the fact that this was pre-dvr and pre-internet. She could have gotten his speech later.