The main reason why the audio does not play smoothly for you is that you may have low bandwidth (less than 56 K) which is not enough to provide you with good audio and video performance. You are suggested to turn off your computer’s sound to be able to watch the video.
Also in order to advance playback quality you may get a faster modem. DSL connection will enable you even with better quality! However the simplest way to improve video viewing is to pause the video to let it be buffered. The more it is buffered, the better it will look.