The Role of Vengeance in History

"This is not, you know, as uplifting maybe as some of our other Christmas episodes," he says. "I think to some extent the things they have lived through make it impossible for me to fully morally judge them even for the bad things that they've done." A German Jewish musician has a song about this whole story called 6 million Germans by Daniel Kahn and the painted bird. The episode airs December 25 at 9 p.m. ET on CNN.