An extra who played a Navy SEAL during filming of Revenge of the Fallen recently shared his experience on the LS2 Forums.  Light spoilers:

I’m in it as an extra. I am a Navy Seal doing a battle scene against the Decepticons. I filmed out at White Sands and on Hollomans flight line. Filmed for 4 days and had a blast. [...]

I had to chase a bunch of villagers out of the area because the Decepticons were attacking, then had to protect Optimus Prime’s body. There were a shitload of us out there.

The food and catering was awesome. A lot of downtime. Just like a deployment.

I did an interview for the DVD. We will see if that is on it too. The asked me a bunch of questions about the military. The autobots are behind me on top of a sand dune. I did a GM plug. They liked that.

Micheal Bay loves the military. I got to speak with him very briefly. He gets so angry on set at the actors but doesn’t dare yell or demean the military. It was a trip. He said something to me like do you want a job as a DA (Directors Assistant), I said hell yeah. He was getting pissed at his DA. His DA was like trust me you dont want this job. [...]

Another scene was Optimus getting dropped off by a chinook. I had to run up to the area then stop as Optimus was getting dropped.

Another was with Josh and Tyrese when they argue with The President on the flightline. I am in the background.

As much time as I spent filming (9-10 hours a day for 4 days) I hope I am seen at least once.

The “protecting Optimus’s body” part originally had people speculating that Optimus could die in this movie, but if so, then why would an entire action sequence be centered around protecting a corpse?  I know that’s not utterly foolproof logic, but chances are the big guy just gets incapacitated for a while.

It’s amusing to hear that Michael Bay gets really angry with the actors on set.  It reminds me of what the Star Wars cast would say about George Lucas: that he’s not good with actors and only ever has one note — “faster and more intense.”