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%.