Erin from EditorsNet alerts us to this interview she conducted with Ben Burtt. Star Wars fans will of course know him as the sound designer for all the Star Wars films so far, as well as co-editor of The Phantom Menace and lead editor of Attack of the Clones:

For the "Speeder Chase," we shot some of our crewmembers playing the parts, so it was like a home movie. It was actually shown on a screen to the actors, who then took a lot of their timing from the cut, much in the way you might pre-record music for people to dance to so that the timing is right. In the case of the "Speeder Chase," we had a fairly tightly cut sequence that they could watch and respond to. They could get pumped up. They could actually see the context where their acting was going to be, because for many of these sequences the actors are just sitting in front of a greenscreen while the director is saying, 'Turn left, turn right, duck!' This gave the actors something to help them see what it might be like.

Hit the link above for a very detailed and insightful interview.