What I saw: Woman dressed in black, hiding her face with 'something' in 1928.
My explanation: Dressed in black could indicate a widow - in which case, the object in her hand could be a handkerchief dabbing at her eyes. It's hard to make out lip movements on the footage (I picked a shorter clip), but I've seen older people (like when my grandparents were still alive) who would mumble to themselves, or even recite the rosary (also in keeping with 'something' in her hand.) It's also possible that - as a random person walking past a film set - she was simply trying to avoid being caught on film, and muttering about 'those horrible Hollywood people'.
When you hear hoofbeats, look for horses before zebras.