Not sure if this is what you're looking. I use MacTubes. It is free. Not all YouTube Videos can be download, but most can. After it is downloaded I use Toast Titanium to burn a DVD

MacTubes is a YouTube video player and downloader. iTunes-like user interface and easy operation. You can create playlists and download video files.

https://www.macupdate.com/app/mac/28608/mactubes