Just a quick tip for those people that have a slow internet speed.
If you press play and the video starts and stops periodically, it is because it hasn't fully downloaded enough data on you computer to show the video uninterrupted.
To fix this problem, simply press play and then press pause right away. This will trigger the video to download. (You can tell that the video is downloading by the little grey bar sliding across the line at the bottom of the video screen.) Wait a few seconds, up to a couple of minutes; and then press play to enjoy the video without those annoying starts and stops.