It may not be news to some, but I seem to have discovered that if I surf YouTube without logging in (which is 'always'), and if YT tells me to 'log in to confirm your age', I can copy the web address, then start 4K Video Downloader, and click on Paste Link, 4K Vid downloads the video without any trouble. Not always, but I just did it with another one successfully. Then without even visiting the download folder, I can right-click on the vid, then click on 'play' in 4K Vid, play it, then either save it, or right-click on it and choose 'remove'' or 'delete'. All with a blocked vid that YT symbolically infantalized me by demanding that I 'log in first to confirm my age'.
BTW, 4K Vid has been offering me a 'free license' lately, although I'm already getting what I need with the unregistered version.