Brit Cruise is a producer of eductional videos. His latest project, funded on Kickstarter, is called "Gambling With Secrets", an intro to cryptography.
I really liked his explanation of public/private key cryptography : How do you share secrets, when someone is listening to everything you say ? The trick is to use one-way functions, that are easy to do but (very) hard to reverse, like mixing paint :
Brit Cruise is now a Khan Academy professor. :)Manu