The second video is on the disease of going for a powerful but slower Yum Chui.
This internal-like habit is prevalent among those who have learned Tai Chi before. It is not a good habit to have. Granted, it might look nice in a public demonstration, vowing those who don’t understand what combat is about.
However, in combat if you can’t get your strike in quickly when the opponent is in your sight then chances are you will not be able to hit him. This video is meant to eradicate unnecessary punching movements in favor of a lean, minimal, straight to the point movement.