Download from YouTube

best quality download :

youtube-dl youtube-dl -f "best" http://www.youtube.com/watch?v=P9pzm5b6FFY
youtube-dl -f best https://www.youtube.com/playlist?list=PLCuRg51-gw5VqYchUekCqxUS9hEZkDf6l
youtube-dl -f "bestvideo[width>=720]+bestaudio" https://www.youtube.com/watch?v=OHvY1DUxzfo&index=3&list=PLCuRg51-gw5VqYchUekCqxUS9hEZkDf6l
pip install --upgrade youtube_dl

References :

https://rg3.github.io/youtube-dl/
http://askubuntu.com/questions/486297/how-to-select-video-quality-from-youtube-dl