Get the Flash Player to see this movie.
The video starts immediately, but if you want to move back and forth within the video, you can do that only after the video is fully loaded, which shows when the bar below is totally gray. When the bar is totally gray, moving the arrow in that bar will take you to different places in the video. Using the arrow underneath that bar, you can review, repeat sections or move forward when the bar is totally gray.
If you want to watch the entire video, simply let it play.