THis is step by step tutorial that explains how to download video from youtube and convert it in mp3 on Linux. This also works on Windows , but it’s simplier to do it on linux.
Download youtube-dl from this LINK . There are many ways to install it on your Linux, I like to use pip command
sudo pip install –upgrade youtube_dl
After you install youtube-dl , just run command from Terminal
youtube-dl –extract-audio –audio-format mp3 YOUTUBE URL
For example I downloaded http://www.youtube.com/watch?v=y6Sxv-sUYtM with command :
If you want to download video in .mp4 format use command
youtube-dl YOUTUBE URL