Dishita does it again. Within days of the addon failing due to Youtube getting smart, a patch was issued followed very quickly by a full re-write. Absolutely amazing piece of software, and service is the best.
I have used this addon now for several years, and rarely for me, donated to help keep this addon going. The addon download button is embedded in the Youtube page you have open, and you have a choice of formats for the download. It is VERY quick, no set up, no fiddling about with URLs, just a couple of clicks and you've got it. I was really bugged when the new Youtube format arrived, but next to no time, new version available. Cannot be beaten for anything.
I have no association with the author other than being a very satisfied customer.