The first few minutes of this video are dedicated to a brief explanation about psoas- introducing you to where psoas is in the body, what it's functions and wisdoms are. The book I read a short passage from is called "Core Awareness" by Liz Koch.

We then move into the body with cat/cow and a reclined twist- both of which appear twice in the practice for an experience of deepening. Primarily reclined asana are in this class.