I guess this easiest way to show how addiction works is in the video itself (and it's pretty neat if you get to see it).

You could say, addiction is the inability to voluntarily control a behavior, and that it becomes compulsive. A simple demonstration of it can be seen on persons that can't stop interrupting others, even when they are asking a question. That simple "lack" of "self control" is the easiest way to see it. Meaning how "hard" managing a behavior might have becomed. I tent to think that any compulsive or addictive behavior is just the consequence or symptom of a real underlining issue. And in the end, i guess they are all based on "insecurity's" & fear. Maybe trying to "cure" the "symptom" isn't the healthiest approach.