stammer ['stamər] verb [ intrans. ] speak with sudden involuntary pauses and a tendency to repeat the initial letters of words.

I checked the video once more, and I have to say, I did not see much stammering of Krugman until the last 55 seconds. He looked pretty comfortable, and was not hiding eyes. The description above does not really apply to this video. In particular, Krugman's face language was good when Cavuto mentioned 9/11 first time, and still fine even when he was accused of lying.

There were 2 appearance problems for Krugman: Cavuto was not allowing to talk and finish arguments around the middle point of the interview, and then 1-2 min. before the end. And with the last minute, Krugman was flattered by Cavuto saying how great economy now must be despite "corporate" and "stock" bubbles collapsing (presumably in 2000).

But on the other hand, Krugman did not have much interesting to say. His main argument was that "majority of people do not think that the economy is great" - which is a weak proposition. (How does he know what people think?) Foxnews viewers had to hear more how unequal the wealth distribution is.