I found this interesting, so I tried: I recorded a HD movie on Netflix in Firefox, recorded using simplescreenrecorder on KDE5 in Xorg. I remember it was impossible to record shared screen in old (Ebay owned Skype).
It's not just Firefox though, if you're running Chrome on Windows or Mac, you get the same 720p as Firefox.
The only way to get Netflix in high def (1080p and 4k) from a web browser is to use a browser that is made by the same company as the OS it's running on.
e.g.:
- Microsoft Edge running on Windows 10 or 11 (if running Edge on some other OS, output will cap at 720p)
- Chrome running on Chrome OS (if running Chrome on some other OS, output will cap at 720p)
- Safari running on MacOS
In any scenario not listed above, Netflix serves a max of 720p.
