I think the Disney Video's / DVD's are great for younger children. We bought one for our DS before our first trip when he was 3 1/2. We would watch it all the time. It really helped him understand what we would be doing, seeing, etc. What rides there would be, what attractions he might want to see, and which might be too scary for him. For instance, there was a segment about Fantasmic. He didn't like it and didn't want to see the show. We watched the segment over and over and over. Finally, when we were at WDW, he decided he could see the show IF we sat at the very back of the amphitheater. Now he loves Fantasmic and begs me take him to it.
Get the video and share it with your kids, it'll help when you are there...
shelly