You-Get is a tiny command-line utility to download media contents (videos, audios, images) from the Web. Download videos / audios from popular websites such as YouTube, Youku, Niconico, and a bunch more. (See the full list of supported sites).
Install it using pip or brew for Mac:
pip3 install you-get
brew install you-get
Simple Usage to download file from youtube:
Try it out I am sure you will love it. It has been a live saver for me.