My Firefox was having issues with YouTube videos lately. It's double buffering at the start of video playback and seems to be stuttering on some parts, like skipping or going back a second. It only started happening with FF 96 updates.

I got so annoyed that it wasn't happening with my secondary GX browser. I started searching and found a thread leading to this addon and bam. It fixed the very problems i was having. No more buffering, no more stuttering/lag/skip, etc. Thank you so very much.