First of all, I know that this thread has been dead for 2 years now.
Second, here's another workaround which worked for me and you would need Adobe Flash for this to work. This totally eliminate the video loading time.
- In Adobe Flash, create a new Flash Project.
- Set the stage of the Flash project to the same size as the stage in the Captivate project.
- Copy the background from Captivate project to the Flash Project.
- Insert the video into the Flash project.
- In the Flash project, set the coordinates and size of the video (This would be the same coordinates and size that you want the video to appear in the Captivate project).
- Publish the Flash project.
- Insert the published Flash project (SWF) to Captivate as animation.
- Set the animation as if it is the background of the slide.