As a connoisseur of monad explanations (if not monad understanding) Crockford's talk sounds rushed. It spends a fair amount of time on setup, but when it gets to the meaty bits, it has the feeling of glossing over the details. It could be that all the essential elements are there, but they're covered to quickly to impart any comprehension.

Actually, Crockford is completely wrong in his definition. He is confusing them for functors.

Cool thanks!

I actually prefer Brian Beckman's explanation:

http://www.youtube.com/watch?v=ZhuHCtR3xq8