John --
Instead of directly opening the link, try downloading the MP4 file (ctrl-click? or right-click to pop-up the context menu, then save the link). If QuickTime doesn't like the encoding used in the MP4 file, try the VLC video player. Google for it. It runs on almost every platform, and can decode almost any video format. I use it on Linux and my Mac. (I have no hidden interest in VLC. I'm just a satisfied user.)
- Dave