Doesn't work on 720. Might work on 480, but 480 streams fine for me.
It seems to increase the buffering speed overall of youtube, but will not complete an entire video. My video does buffer faster, but not fully.
Just tested if something might be blocking the extension:
about:config media.mediasource.enabled setting it to false will fully buffer a video that this extension only buffers around 20-40 seconds worth

This is a wonderful extension that allows unlimited buffering of video in any resolution. The settings are thorough and make the extension very customizable.

The only small issues are that it stutters when seeking in 4k, breaks sponsorblock, it's limited to 140s buffering in incognito, and downloads are all 720p for some reason. These are only nitpicks.

Overall, this extension is amazing, and I am grateful to the developer.

I miss when youtube used to let me buffer an entire video.

Luckily with this extension I don't have to miss it anymore.

Honestly probably the best extension I have installed since I have a poor connection where the video where the buffering is often MUCH longer than the video itself,
so I can just leave the video buffering for a few minutes then come back to a perfectly smooth watching experience on any website!

It looks great! I absolutely love the audio EQ section. EQ is something that I've wanted on the browser for years. Only had it for a couple hours at this point but once I figure things out, its going to be the default for me. Having some trouble with youtube live streams...it can't seem to find anything to play. I need to work with it more to figure out why...

works as advertised perfect for when my busy home network is very active since using it youtube has not hitched or stutter at all only issue with this addon is the auto detect feature seem to not work when opening youtube videos in new tab requiring a manual selecting otherwise my time with this addon has been awesome

I really like this :)
I've been looking for something like Twitch Alternative Player for other sites for a while now and this seems to work well enough for what I've done with it so far. For youtube specifically, it would be really good to be able to make it Theater mode and if videos started by itself (right now I have to press the play button after the site loads), I might use it as default if these things are implemented. Thank you for the extension!