That is the specific statement I remember lol, I watched the video embedded on that page. If you haven’t already, I suggest reading/listening to the whole thing because it’s quite funny yet informative.
So Krugman doesn’t understand the difference between paying a domestic debt and paying a foreign debt. And that’s because he doesn’t understand foreign trade.
If he understood foreign trade and debt, he never could have won a Nobel Prize. A precondition for winning the Nobel Prize is not to understand how international finance works so that you can act to preserve the kind of financial superstition that’s taught in the universities like the University of Chicago.