I'm having problems playing back video on my Mac Mini (hooked up to a Samsung Plasma) using all varieties of media players, including VLC, Quicktime, and iTunes. Regardless of the media file (SD, HD, various bitrates) it always appears choppy/studders. Yet, when I playback video in PLEX, I have no problems. All of my media is kept on an external HDD connected to the mini via FW800. When I playback any of the media on any other device--macbook connected wirelessly (802.11N) or streamed to an TV I also have no issues, video is very smooth. Any ideas what is causing the problem?