Best (short) video explaining Ethereum and smart contracts?

Can anyone direct me to a great youtube video explaning Ethereum and smart contracts, that is between 2 to 4 minutes? I am helping out a friend with a presentation at work and she is looking for a great intro video, to kick off with.

Thanks for your help!

Edit: found some great ones in the sidebar. If anyone has any other suggestions that would great too.

Submitted February 05, 2018 at 08:33AM }
via reddit