It was the blink together with the facial expression. That plus knowing who she is and how people of her type generally think about people on the right, especially on issues like this one, where they are 110% convinced it is truth and deniers are stupid and/or nuts.
It was a look like, “Yeah, go ahead, let’s hear what you have to say”, while thinking to herself, “I know it’s going to be some kind of anti-warming BS”.
Watch it on full screen. At just about the 2-sec mark in the video she does the blink and at the same time makes a face, IMO, revealing, be it subtly, her inner expectations of what Carly is going to say.
When you roll your eyes, your eyeballs look up and roll to one side or the other. Your eyelids don't shut.
What Couric did was to blink because her eyelids closed and then opened.
But how you arrive at all of your speculation, supposition and inference about what Couric's motivations, intent and thoughts were from just a normal eye blink is beyond my abilities.
Let's just stick with the facts. She blinked. And so did Carly. People blink. It's normal.