The sad thing is that a "real human being" is capable of laughing at a funeral. I've done it myself, when telling a story about the one who's no longer with you. When my Uncle died, I told a story which some in my family had forgotten, and others had never heard, that brought back memories, and everybody was laughing hysterically. It's possible to lose someone you love, and laugh from the gift of the impressions they made on your life.
But Clinton saw the cameras and realized that he wasn't giving the impression that he wanted to give. And instead gave an impression quite different than what he was hoping to give.
Mark