As a vet television and cable editor of prime time hits, this is one of two downloaders that consistently works.
[*Edit]: Have to let you know however it has stopped working on some YouTube a/o today...

https://www.youtube.com/watch?v=5pe8qsPpDGg&list=WL&index=2&pbjreload=101

iMac Pro 2017 Mojave 10.14.6 Firefox 84.0.2 (64-bit)