Hi.
Extra large videos played at high frame speeds can cause processing problems with the Flash player. What is the processor speed of your computer and how much ram does it have?
What are the size of the video files you are working with?
Have you done a processor test (through the task manager) and watched what your processor is doing while it is loading and playing the videos? That may give you some insight into where the problems are occuring.
Regarding your questions:
1. Resizing the video should not cause a problem.
2. Matching framerate is primarily an issue that affects audio sync. You should make sure your video framerate is a factor of your source video framerate.
3. You may want to link to an external .mov. Have you tried that to see how it works?
4. Dropping the framerate will reduce stress on the Flash player. It may help.
5. What do you mean by increase the buffer?

jb
http://www.wildform.com