I remember seeing a website where people upload videos of themselves writing code. However, I can not find that site now.
The purpose is to see how others code, to see how they refactor their code, to see how they use their paradigms, etc.
Update: I remember that the video contains almost no audio, it's only one guy writing code, making mistakes, typos, fixing mistakes. If I read the final code, I can figure out how it works, but if I see how the code was wrote and what kind of mistakes were made along the way, then I can better understand it. I guess this is the main reason that they make this kind of video.