Curious this story...
I am not sure what to think of it. Would it be newsworthy if it transpired that Churchill or Roosevelt told jokes about members of their entourage? I think not. One would almost expect it of them - after all they are remembered as rounded human beings...
There, I think, is the heart of the curiosity. The fact that Hitler told bad jokes rather reminds us that he, too, was human; he had a sense of humour, he liked to laugh.
And this doesn't fit with the monster that we know had millions murdered and started the most costly and destructive war in history. Surely, that same man, that monster, can't have told jokes about Goring's underpants?
Well, this goes to the heart of a problem that I've wrestled with for some time. For many of us, to present Hitler as a one-dimensional monster - a carpet-biting, foaming-at-the-mouth, rabid, ranting, lunatic - perversely presents a rather comforting image. It makes him not one of US, but something else, a breed apart. Therefore, we don't have to think any more deeply about what motivated Hitler, what moved him, what impulses drove him - because they were all patently perverse and depraved.
This may be comforting, but it is a cop out. If we want to understand Hitler, we have to understand him as a human being, with human emotions. This, I think, is where the film Downfall was so brilliant, because it presented Hitler - arguably for the first time - as a rounded human being; polite, avuncular even, to his secretaries, fond of apple cake, but also desperate, and fearful.
This was closer to the real Hitler. If you need your monsters to be one-dimensional, then fine, be surprised that Hitler told bad jokes. However, I would argue that the monster is made all the more terrifying, all the more potent, if one reminds oneself that he was, after all, human - just like you and me.