c# - Downloading video from YouTube

Question

I wish to download a video from YouTube and then extract its audio.

Can anyone point me to some C# code to download a video?

For clarification purposes, I already know how to extract audio from a .FLV file like these.

Answer 1

I've written a library that is up-to-date, since all the other answers are outdated:

https://github.com/flagbug/YoutubeExtractor