I also have problems with this experiment as well, although I am not trying to claim in any way that there isn't a significant amount of harm done by cigarette smoking (I'm actually a smoker). The problem with this experiment, aside from the one in the first comment, is that it doesn't in any way replicate what's going on with smoking. When I smoke, I hold the cigarette, inhale, and exhale - and what comes out? Nothing? No. Smoke does: most of what I inhaled is coming back out. Furthermore, hardly anybody 1) smokes a full cigarette (there are some who smoke it to the filter but I've never seen anybody do it - as for me, when I smoke, I usually smoke only to the halfway point anyway because I make hand-rolled ones and don't like to burn my fingers) or 2) inhales all of the smoke that comes off of the cigarette. My guess is that the amount of smoke a person inhales that could come off of a single cigarette is roughly 70% of the smoke produced by the cigarette.

Thus, the experiment - an experiment whose results are very interesting to see, and which I enjoyed watching greatly - is invalid. And considering the harm with this, I don't really have a problem with it. On average, most people are removing 2-3 years from their life by smoking.