The mere existence of a second Mary Bronstein movie, much less one as amazing as this, proves that patience and a bad attitude are not just their own rewards. If I Had Legs I’d Kick You, her second film and her first since 2008’s Yeast (one of the best American films of the 21st century), is a masterpiece of alienated frenzy. It’s a comic version of The Exorcist in which the mother is the one possessed.