Worked for me!

Video screen is black when VP9 is blocked. How can I fix this? Everything was working fine until recently.

Helped bring down my CPU usage from ~30% to around ~15%.

Works great, but it seems to break livestreams.

Works great on my system that's missing h264 support but has decoders for VP8, VP9 and AV1. Previously, I would be unable to play some videos since YouTube didn't seem to be able to figure out that h264 was unsupported, but since installing and configuring the extension to block h264, I've experienced no issues

It broke youtube for me and today i finally figured out this addon was the reason

This extension is a must for weak notebook CPUs that only supports AVC1/H.264 Hardware Decoding.
I also don't know what other people talking about... This addon is giving life on old CPUs systems like Sandy Bridge, Ivy Bridge, Hasswell etc that they only supports AVC1/H.264 hardware decoding. This addon forces Youtube to use AVC1/H.264 instead of VP9 or AV1 codecs. Of course they are some limitation from Youtube, you can only play videos on 1080p@60fps but it's a lot better to use HW decoders than software for many reasons. Of course one CPU with 4cores&4threads like Sandy/Ivy/Hasswell can decode an AV1 4K video in software mode or in VP9 with the perspective bitrate but it will use almost all of the CPU horsepower, meaning you can't do other tasks.The same thing happening with H.264 even at 1080p, the CPU usage will be ~30% with software decoding mode. With hardware decoding the CPU usage drops to ~10%.

Ive played a few videos after installing the add on, and checked stats for nerds which showing the codec as avc1, (which is H.264) so it does appear to be working correctly by blocking VP8, VP9 and AV1

I have no idea what the other reviewers are talking about. Before blaming the app, perhaps you might want to take a look at your firefox's about:support settings and make sure that your settings/OS/drivers aren't blocklisting the h264 functionality. This project has made my old Sandy Bridge i5-2435M, Ivy Bridge i5-3320M and Haswell i7-4960HQ fully USABLE in the year of our lord 2025.

Of course certain iGPUs aren't powerful enough even with AVC decode (thinking about my first gen Arrandale i7-640M) on 1080p, but hell, this thing just works! Thank you for continuing this project Alex.

Not only would videos not load, but it continuously tried to play an ad for a specific adblocker when enabled

Thanks to this plugin I was able to resolve iGPU heating issue on MBP 16 2019 which is not capable of natively decoding AV1 content. I needed to disable only AV1 and keep VP9 so I still can play 4k 60fps content.

stopped working now (probably beacause youtube did something). if you use this loading parts of the video will just get slower.

On a lot of videos if I block h264 and AV1 the video won't play and it says your browser cant play this video. Add an option to "Activate VP9 when it's available".

Работает, но каждые 10 секунд пропадает звук на 2 секунды....

Great can work on Firefox for Android too