There was one question that remained after the class: what is the red line between the MCH-Thigh_ik and MCH-Shin_IK on the constraints in the leg rig schematic?
Wayne will confirm, but I'm pretty certain that is indicating the IK chain! It starts at the head of the Foot_IK bone (the control bone), and goes up to the head of the MCH-Thigh_IK bone!