Obtuse menus. It puts a QR code on the corner of the videos which costs 18 Euros to remove. Terrible. You can get better functionality without the QR code from other video downloaders, cannot understand why this is recommended.

Funciona muito bem em diversos sites. Satisfeito com o resultado.

Very easy to use and very reliable for downloading videos that one cannot simply right click to download.

I have been downloading my videos with it for years. The best tool until now.

ottimo componente aggiuntivo di firefox, esegue il download della maggior parte di video online

Excellent application. I wish it would work on more web sites but in the ones it does, it is great. Thanks "Video DownloadHelper" for this add-on.

FAILS on firefox (gnu/linux) and "companion app" available for microsuck only.

QR code? No, thanks

Das Ad-on funktioniert einwandfrei, besser als anderes, was ich bisher verwendete

VideoDownloadHelper is, conceptually, a great add-on for Firefox. I feel, however, that the product (sadly) still has some further thought needing to be put behind it to turn it into the kind of download helper that it could, and, should be.
When it works, it usually works well. Sometimes, however, for no reason, it does not work.
My biggest gripe, actually, is that the functionality is very esoteric / arcane in that the developer, even with the right intentions, has not "translated" the functionality into something that is easy to use / intuitive / friendly. Frankly, I find this a bit odd -- how does one not find out from potential users what their issues are, etc.?
There are still quite a few aspects to this add-on that, frankly, I have no clue about, and, can't make sense of. And, by the by, I'm an above-average tech user, so, I SHOULD be able to follow the logic easily.
So, so ... not meaning to be harsh. This product, 70% of the time, is very useful. I urge the developer, though, to elevate this app to a "100-percenter" which would be amazing, and, which would become a major money-spinner for said developer. Right now, it's a half-job, sadly, though, still worth going through the motions to use it, as, often, it does work well. I think (maybe?) a first step for the dev. should be to make usage of the add-on a LOT clearer and easier. I mean, this is overly obvious. From there, some good tweaking / researching users would / could make this a fine add-on.
My humble 5c worth...

このアドオンなくして私のfirefoxライフは成り立ちません。本当にありがたいです。

NB Plus

niu b，very good！！

I love it, it does what i need it to do.. YMMV

Unclear, problematic, can't even download single youtube video. Even if it accidentally starts it is so slow, 1 minute low quality videos can't be slowly downloaded as webm like that. Looks like a joke. Never had luck with this extension really.