I've seen the TheraBite video and it is pretty self-explanatory. While I did not use the device, I have heard from many that have and found it effective. I used the old idea...stacking wooden tongue blades between my anterior teeth, each day pushing myself to get one more on the stack during treatment. Before radiation I could put about 16 of them between my teeth, my goal was to see that number stay the same all the way through treatment. As trismus takes effect, the muscles are less elastic and this becomes progressively harder. Scar tissue builds up in them and this does not reverse itself. So the idea is that each day you try to keep stretching the muscles to keep the scar tissue issue (say that 10 times fast) at bay. It will not prevent the formation of the scar tissue, but it will increase the elasticity of the muscle overall and keep the ability to open your mouth fully at an expectable level. By the end of treatment I no longer could do the same number of blades, but I was close to it. If you do not pay attention to this, you could be in a situation where eating is a serious problem let alone the issues of speaking and diction.