That seems strange. Did all of the other vids in this thread play back for you?
All I can tell you at this point is that I have the K-Lite Codec Pack installed, and the vids played fine for me.
http://www.k-litecodecpack.com/
Another option you may want to consider is installing the VLC Media Player. I use it when I can't get a video to play, and I've yet to come across something that it wouldn't play. It's an excellent back up.
http://www.download.com/3120-20_4-0....=9&search.y=11