There was a time when this downloader worked, but sadly it no longer does. YouTube has declared war on downloaders and none of them appear to be working now...
Either fix it or remove it...

무한로딩...

This extension is pure bullshit, so hands off.What was promised does not happen. In other words, there is no video download.

APOS!
A Lite addon?
Ya, Lite as air, 'cause air is all you get!

В тёмной теме YouTube чёрная кнопка практически не видна. Выдаёт много вариантов видео и mp3, но ни одна загрузка не стартует.

не работает

No aparece ni el boton

Ni siquiera aparece el botón.

No download button. Screenshots are for the older Youtube format, maybe that screwed something up?

No download available. After install, restarting firefox or rebooting the PC.

No download button.

No download button.

Не работает.

Doesn't detect videos

No download button.