Wondering who is open to being filmed during their sessions? I can think of Kristy in NVan, Sandi Laine, and Petite Lauren, but haven't seen any of them post an ad in a while.
Doesn't happen very often but if you can establish a good rapport with the right lady and aren't creepy, some are open to it at no charge (YMMV). The best one, by far, is the one who ASKED ME if I wanted to shoot some video, just out of the blue. It was pretty kinky I must admit and was more satisfying than most of the videos I made with g/fs in the past because it was so random and impromptu - no planning, just hit record and fuck.