This clip involves the professor engaged in a discussion with a group of students who are working together on a problem at their desk. Namely, the problem focuses on finding the area under a velocity vs. time graph. The professor asks the students to make their findings more general by using a variable time, t.
This clip takes place in week 3 (Becoming Quantitative with Constant Acceleration). The problem being discussed is from page 2 of the Becoming Quantitative worksheet. The goal of the worksheet is to develop the equations for constant acceleration.