L’esprit de l’escalier I think can be loosely translated as facepalm. That’s my best guess. He hits four or five other words in that bit of audio from All Things Considered back in 2005, including farpotshket, an expression that happens to me pretty much every time I try to fix anything. I especially liked l’esprit de l’escalier because who hasn’t had a witty or clever riposte occur to them as they are leaving a conversation and it is too late to use it.
L’esprit de l’escalier happens to me. All. The. Time. It happened just now. It happened when I read farpotshket on a friend’s Facebook wall and went looking for the meaning of the word (and pronunciation. I mean, WTF? How is that pronounced?) only to have the response lost before I made it back there to post this link. The spirit of the stairway simply doesn’t do the expression justice.