It’s true. From time to time there’d be a casting call for extras or whatever.
My body wasn’t in any of the Lucasfilm movies, but my scream was. There’s a scene in Indiana Jones and the Temple of Doom where Indy’s crossing a rope bridge above a river filled with alligators. People fall off the bridge, scream, and die. Master sound designer Ben Burtt asked for people to volunteer to scream. When it was my turn, I walked over to his small sound studio. It was darkened (so people wouldn’t feel as self-conscious), and he then put headphones over my ears (maybe so I couldn’t hear myself yelling, but could still hear him). Then he directed me to scream in various ways… as if I were getting shot in the stomach with an arrow, falling off a bridge, etc.
I was hoarse for the rest of the day but felt strangely elated and relaxed. I know there was a New Age therapy called Primal Scream. I think that’s what I experienced. I actually heard my voice (I think) when I watched the film.