I would give zero if possible.
This extension literally does nothing. Complete piece of dung.

Ad riddled malware

Fine

NOT WORKING.

Doesn't work, shows only plenty of ad

was not able to download anything above 640p

Unable to download some videos and recomends to pay for some desktop application claiming it is impossible doing so in the add-on and recomending to pay for a desktop application, even though tools like hls-downloader are able to do it in an add-on.

d

It kind of works, but with multiple video resolutions available it will only let me download the lowest resolution

Very good addition to Firefox. It does the job most of the time and only a few slip past it.

A hidden money maker machine.
It can download fewer file types than other add-ons and then invite you to buy a program from 13.99 to 24.99 dollars.
This should be on the description of this extension.