Youtube have blocked all Addons and third party players as of september 2019..
VLC & Smplayer and so on are all blocked from using URLs to play youtube direct they require a remixer site first.
This plug in is also Blocked from finding URls from youtube when on native youtube site...
But the script on the savefrom.net site is not currently blocked...

On youtube NO links will be found on the drop down download menu as currently youtube are still blocking this extension...

Расширение заблокировано компанией Mozilla. Пишет, что "SaveFrom.net помощник было отключено из-за проблем со стабильностью или безопасностью".
https://blocked.cdn.mozilla.net/04c27082-2b78-4005-a6c5-8e0a13f83288.html

ممتاز جداا وشكر لصاحب البرنامج والقائمين عليه

It does not work