看其他評論好像是現在不能用了，的確不能用。

Could not extract signature deciphering actions, sadly doesn't work anymore.

it used to work but not any more so sad to see this go

Hasn't worked in ages.

Has been a really great addon for a long time until it stopped working for me three years ago.
So I did let it live in my firefox out of hope that someday there may be an update which would get it working again.

But I think after three years of waiting in vain, it's safe to pronounce this add-on dead, uninstall it and look for alternatives.

So long, and thanks for all the videos, but I guess it's time to move on.

I was shocked to see that this was still installed. No buttons have shown up for years. It's a totally broken mess that i'm, about to remove.

This was the best youtube downloader available but it no longer works and it appears the developer has given up as no updates for 3 years.

This is pure garbage, not working at all!

Used to be a fantastic add-on but now it doesn't work anymore as it's been abandoned for three years. Should be removed from the add-on store.

This used to be great. I would use it to download the audio from YouTube podcasts, but it stopped working. I found this newer version, installed everything (ffmpeg etc) and it STILL DOESN'T WORK!! I'm so sad and disappointed. I really wish they'd get this working for YouTube again.

Could not extract signature deciphering actions

Does not work.

не работает

it didn't work fine

Could not extract signature deciphering in a youtube age restricted content lol what a lame addon

doesn't work

Ce module n'a jamais fonctionné, il est inutile.

全然使えなくなったエラー出るようになった

Sadly this add on hasn't worked in YT for quite a while now. Give "Parabolic" a try, available for Windows, Flathub and Snap for Linux. Works great.