This is a hoax. Seldom works. Why is it even allowed here as an Add-on. Presumably just to collect information about your browsing activity.

Breaks other add ons that actually worked previously

Junk - doesn't download but opens some website instead.

Takes you to a different page and keeps you there while it "converts" the video.

Very slow at "converting" the video.

it leads to the web page where anti-virus software warns its danger.