You can use various apps to download YouTube videos. Give some of those a try. https://www.techradar.com/how-to/how-to-download-youtube-videos https://www.google.com/search?q=how+to+download+videos+from+youtube&rlz=1C5CHFA_enUS737US737&oq=how+to+download+videos+fro&aqs=chrome.0.0j69i57j0l4.4182j1j4&sourceid=chrome&ie=UTF-8
Or (legally?) perhaps contact Mr. Gilder and ask him if he can make them available for download to you.