This is just a little executable app I made, mostly for myself, but open source, so that anyone can use, and tinker with it. It only uses a few packages, and the code is pretty simple. Basically, you open it, supply a URL, choose a directory, and then slap download! I have it set to only fetch a maximum of 720p resolution, because HDD space is precious to me, but you can totally edit the source code and rebuild it for 1080p, if that's something you want to do. I just don't see any need for it in my version of the app.
Enjoy your ad-free YouTube experience!