the green button is not appearing for Firefox on Ubuntu 18.04

This "recommended" addon won't even let me download vid as audio and pops some HD vid limitation warning while I only want to download mp3 with lousy 128 bitrate.

Generic Youtube videos download fine, but movies don't, and I mean FREE movies; audio files can be downloaded, but not MP4 files. JDownloader works fine, why can't this extension?

NOT FREE

Only does video downloads and not MP3 conversions as it's "advertising", which is why even though it does do the video download (at least the one that it lists for the size on YouTube), I'm giving it a one star because it literally says "2) Single-click 256kbps HQ MP3 downloads" which is not true as you have to pay for the "pro" version or hope some other paid pro user has downloaded and only in the past 24 hours.

TLDR: Doesn't do a major feature of what it says it will do so 1-star.

you can only download mp4 360p. other format need money to unlock... not even a free trial given... how can i trust you

Not free only for youtube pro users wich im not going to ever pay for since ive used youtube since day 1 almost 20 years for free .... Booooo Boooooo to gold diggers ^^

does not work. avoid, it's a loss of time.

this software provides very limited functionality being capable of saving only videos in limited qualities and no MP3-files at all. to me it didn't do most of the things they are advertising on their feature list.

I do understand the developers would love to get some money but sorry guys, too little functionalities available in the free version.

I looked for a downloader with 1080 possibility as I use a free 720 so far. This one promises 1080, but if you want to use it, you must pay.
My trust to Mozilla suffers, when these white knights allow such black ones to make me a victim. So if money is needed Firefox should tell beforehand. Its a question of honour.

In order to actually use the extension's selling point, you have to pay for it. At that point, you're better off recording whatever it is you want to download in WASAPI.

Strange that you have to buy an upgrade to get decent quality files when the excuse is clearly a lie. Jdownloader is able to do it without lying to me about how the files are stored on Youtube.
If crappy quality files and fake excuses to pay for an upgrade sounds good to you then you've found your Add-on.