Re: Ask sensei to demonstrate "at speed"?
At the risk of sounding magically metaphysicial tye-dyed, what I mean by "energy protects," is that the absorbed energy by the uke coming from the Sensei's technique is momentum for ukemi. That by absorbing the energy it is used in various ways to help with doing good ukemi or assisting in good ukemi. As an uke you have to accept the energy of the technique will help you in your ukemi. The more your give your energy in a commited attack the more energy your get back that helps with ukemi. The less energy you give means less energy is gotten back and the extra momentum isn't there to protect you. You have to work harder and be more conscious of your ukemi. You have to make sure your ukemi will protect you.