Hi! Playing Youtube FullHD videos in full screen mode shows under "Statistics For Nerds" that the Html5-player uses a lower "dimension" than the video's original 1920x1080 and scales it up to fit the screen (x1.2 at a FullHD display in my case). This way there is quite some resolution lost and the video doesn't look as crisp as it could. Setting "layout.css.devPixelsPerPx" in about:config to 1.0 resovles the issue with the video resolution but makes everything else small and less readable. So that's not a fix for me. I would like to prevent this upscaling only for full screen videos but not for images or text for example. I'm posting this from a different computer which runs Vista so if any additional data is transmitted through this form, it is of no use!