He started filming his friends playing and the next day we used imovie on my computer to add music and words to his footage. Here's the movie he made:
He was absolutely wrapped with the result and it was super easy too! With a little help from me to write the words (I needed to get out the dinosaur dictionary to spell some of the dinosaur names that I'd never heard of before) he dragged and dropped his footage into the imovie template. We were done in about 10 minutes!