Macfadyen and Platt talk Frost/Nixon has an exclusive interview with Matthew Macfadyen and Oliver Platt, ahead of the UK release of Frost/Nixon on Blu-ray and DVD on May 18, 2009.  An excerpt:

Did he actually peel off and run naked into the sea too?

MATTHEW MACFADYEN: He might have done. It would have been something that he could have done. I asked him about that. He was sort of hazy but he said it was something he could imagine himself having done. It was a wild, spur of the moment kind of thing. But actually he would have had to get into the car and drive down to the beach and then dramatically, spontaneously run into the sea.

OLIVER PLATT: In real life it was Zelnick who did it but he has a much nicer bottom.

Thanks to SallyG for letting us know.