Does this instability happen when you don’t use a video clip?
What format is the 280MB clip (WMV, AVI)? What codec does it use?
Can you convert it to a different codec that provides better compression? Can you convert it into a jpg image sequence and try that instead?
(The image-file-loading code is older, while the movie code was updated in 3.0.2 and 3.0.3, so if there are issues with movies, there probably are not with image sequences)
Finally, it could be an OpenGL (video driver) issue, so check to see if your video card manufacturer’s website has a newer driver for your card.
Alan.
http://www.wondertouch.com