I bought it with my company account because I needed it for my work. I was going to listen to part 2 right away, but I listened to it as a summary, and it was helpful because I could learn about the updated contents :) The part that was especially fun was the part about analyzing the lib.es5.d.ts file. There were some brain freeze times, but I was able to naturally learn about the limitations of TypeScript and how to do actual type analysis. I once again realized that the most effective way to study in order to understand a language is to dissect the code and structure of the people who created it. I think that Zerocho's lectures are the most practical and suitable for any kind of lecture. I always listen to them well~!