Hi, I just watched this video that some other commenter posted https://www.youtube.com/watch?v=cbeJIwF1pVY https://www.youtube.com/watch?v=cbeJIwF1pVY Where is

Hi, I just watched this video that some other commenter posted https://www.youtube.com/watch?v=cbeJIwF1pVY https://www.youtube.com/watch?v=cbeJIwF1pVY Where is this prof getting it wrong by a factor of 100? What is he leaving out?