Not working anymore - I still have av1.

Currently seems to not be working as blocking VP8/VP9 means videos are played in AV1. Even when AV1 playback is technically disabled in Youtube settings.
For me this is overall worse as AV1 seems to use more resources than VP9.

Correctly installed/setup, but failed to work in multiple instances

Ohh nooo. If you want them to see everything you do in your browser, including user name and password for Where ever you are are. Go right ahead and install this.

It will work but just so you know, this addon removes the settings for above 1080p video quality (like 4K).
It also seems like it has been abandoned by it's current author.

при подключении этого расширения всё стало только больше тормозить, в других сервисах всё работает нормально, так что беда не в интернете

don't work.

After installing this addon, 60fps no longer works. Even when I uninstall it again, or reinstall Firefox. I don't know what it did, the switch to H264 worked fine, but even rolling back everything the videos are locked to 30fps with no way to fix this.

Will not install.

The installation failed. Please check your connection.this causes the error.I've installed it before.

Does not work

rubbish

я не можу встановити

This is THE ONLY add-on that's preventing me from switching to Firefox from Chrome , very disappointing results on YouTube, does not actually do anything.

На жаль, не працює як треба. Потік то стає H264, але FireFox не використовую при цьому апаратного прискорення відео.

I tried testing it on youtubes test page & it never acknowledged h264 so a useless add on it seems.