If the internet connection is not fast enough or too unstable, it will cause the video to "stutter." To see the workout without stuttering, your connection should be at least 6 mbps. Try each of our three quality levels (HD, 480p, 360p) until you find the right quality for your connection. Click on the settings symbol (gear wheel) in the bar of the video player and select the desired quality.
Please also check if you have the latest version of the internet browser installed; if not, update your browser.