Actually, when I listened to it when I knew nothing, I gave up halfway through. I really didn't understand it. But after getting a job and continuing to study separately, I was lost and happened to listen to it again... It was a lecture that solved the points that I had been confused about and organized them as a bonus. If there are people like me who are lost about concepts like prototype, Execute Environment, and Lexical Environment, I definitely recommend listening to it. (However, I don't recommend listening to it if you are really new to JavaScript!)