Isa Mazzei arrived on the filmmaking scene last year with quite a splash. The writer of the Netflix breakout Cam, Mazzei channeled her experience working as a camgirl into the script for one of the breakout horror movies of the year; a sly and, yes, sexy look at matters of online identity, human sexuality, and self-empowerment that offered an unusually candid and empathetic look at sex work. Now, Mazzei is stepping away from fiction and claiming her story for her own with the next memoir Camgirl, a detailed look back on how she became an online sex worker, what …