It all started when Rob Reiner tried to convince Albert Brooks to let him film his own version of “My Dinner with Andre” titled “My Lunch with Albert Brooks.” His high school chum refused. After someone else came to Brooks wanting to make a documentary about him, the financing fell through. Then the men decided to combine the two things.

“There’s about 4000 documentaries now,” said Brooks at an FYC event with Reiner and moderator Judd Apatow this week at the Academy of Motion Pictures. “It’s the way they’re willing to spend money without spending real money. Everyone has a story and 99 out of 100 are done pretty much the same way. Either the person’s no longer living, or they’re being talked about from an off-stage voice. So to be able to do that this way…that’s what makes it special. Because it’s Rob and...