An interesting topic for a lesson!
I think most people know how to download a video from youtube, but for those that dont, the easiest (and safest) way is to go to the youtube video you want and just add "pp" (without the quotation marks) to the url directly after the word "youtube".
For example,
https://www.youtube.com/watch?v=vlkXwL8tFmI&list=RDvlkXwL8tFmI&start_radio=1
would be changed to
https://www.youtubepp.com/watch?v=vlkXwL8tFmI&list=RDvlkXwL8tFmI&start_radio=1