youtube-dl download video format code example
Example 1: downloading youtube playlists using youtube-dl in highest quality
youtube-dl -f 22 'http://www.youtube.com/watch?v=P9pzm5b6FFY'
Example 2: youtube-dl best quality
youtube-dl -f bestvideo+bestaudio/best https://www.youtube.com/watch?v=nYdiDq1fOiM