Except for the fact that not all video formats are 60 frames per second, movies for example are 24 (well, 23.976). Since you can't evenly multiply 24 frames into 60 frame processing used by TV's, they used 2:3 pulldown processing to double certain frames and not double other frames to make playback work on 60 Hz. As said before, some people can see this and it looks like micro stuttering with the images speeding up and slowing down (since that is exactly what is happening). 120Hz fixes this since you simply play each frame in 24 frame content 5 times, and you get 120 frames. For 30 frame/sec content, you play each frame 4 times (many TV shows are filmed at this rate), for 60 frame/sec, you show each frame 2 times. The result is that the playback is all smooth, and in the same ratio as originally filmed, resulting in playback that is as originally intended. It is no gimmick.