The WebKit/win/FullscreenVideoController could be moved in a common WebKit directory. The windows-specific bits should be implemented in a sub-class. This way other ports could reuse the code.
There is an issue with where to put this. There are no cross-platform directories in WebKit. Should it be: 1) In WebKit/common (or something) 2) In WebCore with subclasses in WebKit (ick!) 3) All in WebCore I'm not sure what the best approach is
Not sure anymore this is worth the effort. In the end the common code would only be a few methods, mainly proxies to the HTMLMediaElement API (play, pause, etc)