why there is out of sync in video and audio in a particular website

Adobe  Flash player has no issue on other sites, but on a particular website, when i click a video to play , it is taking time to load the saved streamed video and then plays. Audio is perfect, but the video is out of sync. It is as if it is being gripped and releasing every frame of the saved streamed video. I could not use any other player to play, as that website, has only  flash player to play the video.

                              Why this is . I am having the 8mpbs speed and there is no problem in other sites. I have the latest firefox. I tried other browsers , with the same effect. Uninstalling and reinstalling does not fix the problem . Would you suggest how to workaround to video and audio sync while playing.