I had this sound problem with my downloaded copy of Ironman...

If you're using Windows Media Player, you can go into the "audio" part, and put a delay on the audio so that it get in time with the video..... I only recently figured it out in desperation,,, But i've watched a couple of boxing matches before with the sound playing before the video, and it drove me insane.. I could hear all the flurries before seeing them...