Place finger on surface, then roll finger without lifting or dragging it.
A finger is a 3d dimensional object that doesn't have just one contact point to the touch interface, rather, it has a surface area of contact. Each person's finger is a different shape. Simply rolling a finger isn't going to guarantee that the pointer will move in the direction you want to.
Putting something at a subpixel position is even easier with modern GPUs (and even Intel GMAs) that power compositing window managers.
Yes, representing something in a sub-pixel position is a situation that modern graphics cards handle quite well. However, I don't see how that would be useful in the context of window management on an OS. If I were working on a Photoshop image, I would want my position to be guaranteed integer values as well.
Even RTS or rail shooters?
Have you ever tried to play Starcraft with a trackpad? Try playing it online and see how long it takes before you get frustrated.
Speaking of Starcraft, I find it to be false assumption that input bandwidth of current input schemes is insufficient (which the voice-over of the video claims). Professional Starcraft players are able to perform 300+ actions per minute with a mouse and keyboard. For the average user, I think this would be plenty.