I can create a slider bar in Flash easily which will be used as a GUI in front of the VET scene. How can I use this bar to control some kind of VET contents? e.g. control a ball's opacity from 0-100 while I drag the slider bar?
Use the "extern" object in the flash 5 file to pass opacity values to the VET scene. For more info on using the flash "extern" object for flash running inside the VMP, refer to page 2 of the VMP 3.3 release notes.