QC project

I don't know if anyone has tried to do this but I did see it done at the WWDC 2007 in one of the sessions.

I want to create this Composition that has two sources, a video source and a keynote/powerpoint presentation. I want the Composition to go in between the two sources. I'd like to have the slide be the bigger of the two sources and then switch to the video window as the bigger source. I'd like the transition to go from the slide to video after about 15 seconds. I would then also want to have the video change after the slide changes according to the professor's adjustment. Any ideas would be much appreciated!!!

Erick...