Chrome’s full screen safety seems a bit odd

Screen Shot 2016-03-30 at 21.11.14

If you’ve ever clicked on a video embed in a page to go full screen you will most likely have encountered this (see above). An irritating alert bar informing you this site wants to go full screen – is this ok? But isn’t this closing the gate after the horse has bolted? Why doesn’t this notification appear prior to the video going full screen and block the action.