He makes a good point regarding the mystification of the martial arts. I also believe the "unbendable arm" is not a legitimate display of chi. As he demonstrated, it is a biomechanic thing that anyone can do, and for one to use it as a demonstration of chi is inappropriate and displays ignorance.
Real chi is more subtle, and less tangible than these kinds of obvious demonstrations. It is elusive and difficult to grasp and control, and very few people reach a level of proficiency where they can use it in clear and obvious martial applications. Chi bullets and whatnot don't exists. But I believe chi does exist. It has clear application in Chinese medicine, as well as martial arts. I believe that in martial arts, it contributes in subtle ways, making one's technique, body, and health stronger. But it is often something that cannot be clearly and easily measured and compared, because it takes a long time to develop and its benefits come about slowly and gradually.
Do the results justify the amount of time and practice needed? I don't know. I guess that is for one to decide for himself. Some (most?) may train all their life and never realize any results. But in my opinion, it does exist.