PyTube is a YouTube video download Apache2 Licensed library, written in Python, lightweight, and dependency-free.
Most existing software for downloading videos from YouTube are: bloatware, often trialware, brittle and aren't extendable what-so-ever - and if you sit in terminal all day, I'm sure you'll agree things should not be this way.
PyTube aims to do one thing and one thing well, provide you an API to simply download a video and get out of your way.