This is almost like "Youtube - Lights out" userscript (http://userscripts.org/scripts/show/11058), but with CSS and it works little bit different.

When your cursor is on the page, Youtube looks just normal. And when your cursor is outside of page, like top of Firefox or even in scrollbar, Youtube goes into black and hides everything but not the video.

Notice, it's ONLY enable in video pages.

Simple CSS using body, hover and opacity.

Recommend to use with "YousableTubeFix" userscript (http://userscripts.org/scripts/show/13333)

---- Updates ----

18.5.2009 - Information for those who uses Youtube-userstyle, that change body's background, little bit make changing background easier and added Dark Carbon-version of this userstyle

17.5.2009 - Userstyle released

---- Modifying for other Youtube userstyles ----

If you use some Youtube-userstyle that doesn't work with this userstyle, then you need to edit the CSS: delete body:hover's background code (that says CHANGE T