I have started observing this ever since I upgraded to Mavericks. Earlier [i.e. on Mountain Lion] if I played any youtube video on fullscreen, only video would be fullscreen, not chrome.
Now in Mavericks, I am observing that even Chrome app going fullscreen mode. I am not saying it stays fullscreen even after completing the video, but I find it quite annoying. I just want my video to play fullscreen but I don't want my chrome to go to Fullscreen Mode. Anyone else noticed this ? And is it possible to prevent this ?