I was pointing out the inconsistency of having one but not the other. A button would also be a much more immediately obvious way to go into fullscreen mode than double-clicking the video. Besides, there is a ton of wasted screen space between the buttons on the left and the buttons on the right where it can easily fit.
oh I see what your talking about. I wouldn't call it inconsistent though because the close button is drawn from the window manager not the application.
However this should probably be forwarded to the totem development team, since your right there is a large empty gap for it and some users might not be so inclined to double click the video.