In Chrome, this example works without full screen. The page also suggests that "Originally pointer lock was tied to the FullScreen API. Meaning that an element must be in fullscreen mode before it can have the pointer locked to it. That is no longer true and pointer lock can be used for any element in your application full-screen or not."
Also, just to further reiterate the advantages of pointer lock for HTML-5 games, let me quote the example in the first paragraph of the article, which I think sums it up quite well, although note that with pointer locking the advantages go beyond that of simply implementing first-person shooter controls:
[quote:3688xaux]The Pointer Lock API helps properly implement first-person shooter controls in a browser game. Without relative mouse movement the player's cursor could, for example, hit the right edge of the screen and any further movements to the right would be discounted - the view would not continue to pan right, and the player would not be able to pursue the bad guys and strafe them with his machine gun. The player is going to get fragged and become frustrated. With pointer lock this suboptimal behaviour can't happen.