Originally uploaded by Devon Arbelo in November, the video shows two sets of lungs being inflated. The one from a smoker doesn't do too well, but the healthier-looking lung blows up like a giant, fleshy balloon. Not quite like the one from Doctor Who, but pretty close.
While it's difficult to get any actual information from a six-second clip, we do know a lot about how smoking wrecks your lungs at this point. Take this 2007 study, for example, which looked at 30 smokers (having smoked at least two cigarettes per day for the last year) and 45 nonsmokers (who had not smoked for at least the past five years). The subjects were all women between the ages of 18 and 30. Their "vital capacity" was defined as the maximum amount of air exhaled after a maximum inhalation; that number is usually between three and four liters for adult women. Results showed that nonsmokers had a significantly higher average vital capacity than the smokers — by over half a liter.
Basically, smoking drastically changes the environment of your lungs. It causes an increase in the number of cells responsible for making mucus, and decreases the functioning of your lungs' cleaning system. This, coupled with the inflammation of irritated tissue, makes it really, really, hard to get a full breath.
For an excellent example of this, breathe deep and check out the Vine below.