On one condition, this would be easy to do in either MediaLab or DirectRT. That condition is, as you have discovered, is getting the PPS translated into a movie or animation file of some sort--i.e., something that will play within a web browser or the Windows Media Player. The only advantage you would get form DirectRT in this case is exteremly accurate timing--i.e., little if any variation in video load time and response time error. If a little variation in timing is ok in your case, then you might as well stick with MediaLab.

So, how do you convert a PPS to a video? Beats me. Never done it. This is off the top of my head and it may seem silly, but what about placing a digital video camera in front of the screen and recording it. Voila, done deal. It would be fast (I know that's a factor for you here) and if you use a good quality camera and save it with minimal compression, it should look great and run fine.

Another option would be to try embedding it within an html file and the specifying that html file as the background in MediaLab. That might be the easiest solution of all.