I had trouble with it before, it was just a setting problem. Now it just completely stop me from watching YouTube. Spent a good 10 mins disabling my extensionsto find out which one was the problem. To my surprise, the add-on meant to improve my YouTube experience caused me the most problems on YouTube. I don't know what they did today, but they broke it.

Save yourself the headache and don't use Iridium.

It was great when it came out, and finally it was a working add-on that could reverse your playlist, and then it suddenly died.
Sadly, the author has been occupied that he or she couldn't update/fix this anymore, so... consider this abandoned.

add-on went to shid a year ago when they decided to totally redo the UI and then just stopped updating it

The writer freaked out because he had to follow the rules and then he abandoned this extension. This is mostly malware now.

Needs a LOT of work before I'll ever consider it again. Intrusive constant pop-up asking for money...NO FUCKING WAY. That's why extensions like this exist...we don't want ANNOYING BULLSHIT like that!

Great extension, an absolute must-have, unfortunately Mozilla has recently decided to be extremely anal about it, so it's no longer supported here. Go to the developers github for newer versions

21.4.2020/// As of today, Iridium completely breaks YouTube's autoplay. Keeps on giving a "playback error". Forced to disable it for now.

Used to be a 5/5 app until the recent updates which removed all of its functions.
Go back to version 0.2.5 if you want this addon to work properly.

IMPORTANT: Use old version!
This is a great extension with many useful features. There aren't any alternatives offering the same quality. Amazing work!
HOWEVER, due to some issues explained on the GitHub page, most of the functions are gone in the current version. Until the functionality is restored, you should use the latest "old" version for now, which is 0.2.5. You can find the version archive under the "More information" section of the store page.

Used to work fine... right now though, it just completly breaks YouTube for me. Not a single YouTube video wants to load while this add-on is active.

It does everything it advertises and blends in so well with youtubes UI. I can't wait till they add more features.

No feature of the add on work, it's complete useless

I loved this extension because of the wealth of features. Until the features return I have uninstalled and gone with a competing extension.

for pity till blacklist features comes back, like in Youtube Plus, this extension is no better than any of several others.