Youtube is a great place to watch user created videos, Youtube provides an unlimited storage for anyone to store videos for free.
Sometimes when we are traveling we took a lot of interesting videos using our smartphone and we often found that our smartphone storage has reached limit and it does not allow us to record more videos, in this emergency time the solution to free some space for our smartphone is to upload the stored video files to Youtube and then remove the video files from our smartphone, unfortunately there is no function to allow us to download our own Youtube video for free.
I have created a simple python script to allow us to download our own Youtube video with audio in the highest definition, please see the Github code in Youtube backup personal video, the code is very simple and self-explanatory.
Anyone can use it and modify the code to personal use.