It played fine for me (in gnome-mplayer plugin). Did you say you downloaded it completely and it still "buffered"?
What were you playing it in?
If it was fully downloaded, and if you were playing it in vlc, there may be some processes overloading your system and preventing it from properly rendering your video and audio in a timely manner. I recommend you get a good graphical process/load/internet monitor that you can put on your desktop, that will help you see and diagnose these kinds of things. There are some free ones available for windows. Here is the CS Fire Monitor 3.01
at majorgeeks - if you're using Win 7 it's possible it won't work, but I think it's worth a shot. Here's a list of monitoring tools
at major geeks. If CS Fire doesn't work, you can check out some of the others.