Ужасно. Совершенно неинтуитивный интерфейс. Поганит качество 4K видео при сохранении, запуская ненужную конвертацию, вставляя при этом QR-код в видео. Аналогично, при операции сведения локальных файлов аудио и видео. Ставит почти 100МБайтный модуль для работы - нахрена столько много? Впрочем, иногда видео в FullHD сохраняет нормально, только поэтому 2 балла.

So many download choices and some of them seem to be the same - I don't know which to pick, and most of the time what I do pick comes with video only - no sound. I could try again, and sometimes I do, but that doesn't mean I'm going to get a watchable video with the next try, and in the meantime I'm wasting data (and my connection has a data limit). On the rare occasions I've gotten something watchable it has a QR code in the corner, which is annoying. In trying to simplify things I've looked for a way to limit the formats I can use but the settings, of which there are a lot, make no sense to me. Basically - this is not very user-friendly and it works only rarely. The only reason I haven't removed it is because I can't find another option that works; if I do this one is going away.

When want to convert mp3, it wants you to download Companion Helper separately. Note it's AFTER you d/l CH and try to use it that it asks for money. Very sneaky, should be upfront and mention it before installing.

日本語可に出来ませんか、頑張て。

Ich habe das Addon lange genutzt, bis es immer mehr zu Problemen kam. Ich weiß nicht mehr, welche, weil ich schon seit langem auf eine Freeware umgestiegenbin.
Die Software macht ihen Job mindestens genaus so gut wie dieses Addon. Ich sehe keinen Grund, wieder zu diesem Addon zurück zu kehren.

This add-on has a very ugly QR Code on the downloaded videos. Time to move to another add-on.

It needs to istall a companion app and don't work without. Требует скачать и установить экзешник, без сторонней программы плагин не работоспособен.

Doesn't work on FF 83. Downloading and converting (conversion app enabled) from Youtube is gone. Neither ADP nor MP4.

It seems to give different options for the video quality each time you try to download the same thing.
When you just click on a download option it doesn't ask you where you want to save or tell you where it's saving it, you have to click on the right-arrow to the right to do that.
It doesn't show you the current download status or tell you when it's done.
The default filename for YouTube videos is apparently just "YouTube.webm" or whatever extension, so if you want to give it a decent name you have to type it out or copy it from the YouTube listing.
It has a ton of options for formats to convert the video to, including at least one audio format, but somehow it doesn't have any good, modern audio formats like m4a, ogg, opus or wma.
It requires you to download and install an external application for it to work, so you don't get the safety of just running an approved and contained FireFox addon, who knows what malware, spyware or adware is in it.
Just about the only good thing about this addon that it's actually able to download videos.
Actually, I take that back.. it only downloads successfully some of the time. Usually on YouTube I get an error similar to this:

Failed aggregating "Paul Anka - Let It Snow - YouTube"

D:\mp3\d:\mp3\christmas\youtube\Paul Anka - Let It Snow - YouTube-IDGEaS6vs8Y.mkv: Invalid argument

I haven't figured out a way around that. I'm lowering my rating from 3 to 2.

Works great for some vids & suddenly stop working, doesn't grab full streaming video anymore

Watermarked unless you pay up.

Most of the time doesn't work, even with the external assist app.

Bild hinkt hinterher! Schade.....

useless

Totally unclear when a file will "convert" and have a watermark on it, even if I choose "download" instead of "download and convert". I never want to download something if a watermark is gonna show up, and I'm never gonna pay for something that an open source project does better. Just don't let me convert something if I didn't pay for that feature!!! Companion application was annoying to install as well. If youtube-dl came out with a GUI version for MacOS I'd never use this extension again. On my windows partition it isn't installed.

it needs a companion app and it doesn't install easy.

While I was happy to try it out I found out that you have to install a converter and that converter writes a large QR code over the right corner of the video which in turn made it impossible to follow the video on how to use a program that I was downloading. Total waste compared to other video converters I have used.