The reason this works for movies and not computer games is simple. Movie cameras let in light in a fashion similar to your eye, and thus at 24 fps motion blur is perceived the same way you see a blur when waving your hand rapidly in front of your face. Games however are rendered one frame at a time, and each frame the positions of everything on the screen are updated with no blurring or interpolation between frames. Thus a higher framerate is needed to achieve a "smooth" motion effect.