The original animatronic Darwin reminds me so of the Skeksis from the Dark Crystal! It's the eyelids, I think. They add an amazing amount of character. That, and the little head-bob he does toward the end of the video.
Of course this is a good picture, but very few people know what he discussing at the time. "And so in conclusion, it is my learned theory that humans have evolved from the lower life forms into the grotesque creatures we see today."