What this is is a clear demonstration of a very real phenomenon: specifically, the power of the human mind to create all sorts of physiological effects on the body just by being convinced enough. Drug tests using placebos have shown this. It's also been observed in studies of native cultures; native shaman in some primitive tribes have caused people to go into cardiac arrest by pointing a stick at them because the person was convinced they had the power to kill them with said magic stick.
Hence, it works like a champ on his students-- who I do not doubt for a second really do think they're felling his chi or internal energy or whatever the hell you wanna call it because they're convinced-- but not on anyone else.
I partticularly loved the disclaimers he used to explain the failure of his awesome mystical dim mak powers on the reporter and the BJJ guys:
1) It only works about 40% of the time...wonderful. Everyone should devote years to mastering a self defense technique that works less than half the time.
2) It doesn't work on athletic types, since according to Sensei Dim Mak Master, they can translate the energy. I suppose it logically follows that all his students are in lousy physical condition, since it works on them...must be a great workout training at his school. Tom Cameron clearly isn't, considering he could barely get his belt around his big fat gut; it's not surprising he would want to rely on Dim Mak considering that he probably can't throw a decent roundhouse kick above the waist. Anyway, it seems his saying that his amazing Death Touch only will work on the sort of people whose asses you could kick by mastering all the techniques most martial arts teach in the first six months because they're out of shape.