Michael, there are probably iPad apps that will download directly, but I know of a couple of good ways to do it on a Mac. If you have Firefox, the Video DownloadHelper add-on works very well https://addons.mozilla.org/en-GB/firefox/addon/video-downloadhelper/
For a standalone YouTube downloader, 4K is equally good...
https://www.4kdownload.com/products/product-videodownloader