Stop Keynote from advancing until a movie finishes playing

I have a Keynote presentation with 3 slides, and each slide contains a movie. I am presenting using a wireless presenter and have to advance the slides manually. I have accidentally advanced the slide before the movie finishes playing, and it is paramount for this presentation that the movie finishes first. Is there a way to tell Keynote to ignore a request to advance the slide until the movie is complete? Again, for complicated reasons, the slides must be advanced manually. Any help would be greatly appreciated.