What happens to the bottom of a dangled slinky when you let go at the top?

I wouldn't have believed it if I hadn't seen it with my own eyes. Why and how can this be true?







And, finally,



. . . If you want to extend your experiments in falling objects, check out this experiment:



. . . and the answer--totally unexpected to me:



Can anyone offer a better/clearer explanation than the narrator provides (beginning at 1:28)? ". . . The tension required to accelerate the chain up actually pulls down on the weight, accelerating it at a rate greater than the acceleration due to gravity." (????!!!!)