Awesome guys! You're probably gonna make this feature accessible via the regular GUI settings page as soon as you deem appropriate, but I hope it's sooner rather than later.
I ended up here in because I was looking for this feature in Firefox. I was hoping I'd at least find an extension or something that would add the functionality. Whether the feature be GPU enabled or not, this feature is a must have. I use it everyday in Opera. I subjectively think it makes every video look better, and I watch everything in 4k (if possible) on a 4k TV. I think I just like sharper imagery vs softer.
I hope a more general shader is implemented. AMD's FSR1 is ideal. I use it with mpv player and its CPU usage is negligible while improving image quality considerably.
May'be it's better to give this functionality to the OS because it's useful for all content on the user device and can be globally disable in OS settings if it makes problems?
AMD has also had a video upscaling feature for quite a while now, but it is not yet supported on Firefox as far as I can find out. I feel like its existence has flown under the radar a bit, as I have yet to hear anyone talk about its implementation.