Great video.<p>Just a warning to any viewers: I think it might be a bit out of date now. I don't think node has promises anymore and I think they also have blocking and non-blocking versions for most operations (meaning callbacks are optional).
It is an interesting video.<p>Quick summary: Node.js is a program/api written in C that lets you write asynchronous servers in javascript. All IO is done through event loops and callbacks.<p>If you are interested in the efficiency/architecture of server programs then this is worth watching.