I copied this from another User, because I feel the same...
AVOID
1. The app forces you to download an outside program before you can use it at all.
2. The videos have big, distracting QR codes in the corners.
3. Downloads were very slow and videos were sideways for no reason.

Firefox seriously needs to review the quality of this app and take down all of the fake reviews.

WHY DO YOU require install a Companion application!!!

you have to pay not to have a big watermark on your video, and this is not mentioned beforehand

Doesn't work on Android.

Requires the installation of additional software (imposed service). I do not recommend it.

Пользуюсь Firefox-ом очень давно, года так с 2008 и всегда ставил download helper, хоть и давно не пользовался им. Раньше был очень крутой и удобный аддон, сейчас же это жуткое днище, требующее ещё и дополнительную софтинку (свою же), скачать видео с Ютуба с этим аддоном тот ещё квест, не рекомедую к установке

CRAP - if it has a QR-CODE on the video - then WHY OFFER IT FREE??? JUST CHARGE EVERYONE - instead of doing a BAIT and SWITCH scam! TERRIBLE!!!

Requires payment to remove QR codes it has now just started adding to vids

Need to pay for almost everything.

C'è poco da fare: non funziona. Le poche volte che rileva un video da scaricare non si riesce a capire se sta effettivamente scaricando il video. Penso sia in assoluto una delle peggiori estensioni mai viste: inefficente e con menù pessimi.
0/10

Requires a companion app that is unsecure and cannot be verified free from malware

A Watermark stick on the video, there is plenty of software do better than this

Watermark switch and bait. Not working as advertised. Holding downloaded video hostage after losing 3 hours uselessly "sum" downloaded video - probalby spending it only for adding watermark.

It adds a watermark and asks for 30$ to remove it!

Ужасное "дополнение", ничего не понятно. Функций нагородили немеряно, а толку нет.

Completely useless. Keeps trying to install some additional app on my computer (probably a virus) and even when installed it still doesn't work.

watermarks=trash

The free version is worthless. I tried to download The Phantom of the Opera yesterday. it tool about 14 hours and the result was more than 2 hours of a blue screen with a QR code.