John Mack interviewed Hank Paulson at New York University’s Stern School last evening. The Morgan Stanley chairman, who recently turned over the CEO reins, told me that he wanted to push some emotional buttons in the former U.S. Treasury Secretary and onetime CEO of Goldman Sachs .

And he did. The two talked about the hairiest, scariest moments of the global financial crisis. Mack credited Paulson with keeping him “pumped up” throughout 2008. Paulson said that in the darkest moments, when Mack refused to sell Morgan Stanley in order to prevent a possible collapse, he feared that if that firm or another big one imploded after Lehman Brothers , the country would have fallen into “something equal to what we had in the Great Depression.”

Their gig at NYU was part of Paulson’s tour to promote On the Brink, his memoir of the crisis. He was on point and knew what to say most of the time, but Mack truly flustered the former Treasury boss when he asked his last question. In a movie version of Andrew Ross Sorkin’s Too Big To Fail, Robert DeNiro will play Mack and Danny DeVito will play Goldman Sachs CEO Lloyd Blankfein, Mack said–yes, dreaming. But given such casting, he asked Paulson, who should portray you? Paulson stumbled, then suggested “a young Paul Newman.” Reconsidering his options, he admitted, “I’m afraid you’d have to bring back Yul Brynner.”

Here’s video from last night.

[cnnmoney-video vid=/video/fortune/2010/03/04/f_sl_mack_paulson_nyu1.fortune/]

[cnnmoney-video vid=/video/fortune/2010/03/04/f_sl_mack_paulson_nyu2.fortune/]

[cnnmoney-video vid=/video/fortune/2010/03/04/f_sl_mack_paulson_nyu3.fortune/]