I don't know about other former (or current) smokers, but I am still attracted to cigarettes when I see them smoked on screen. Of course, when I was a non-smoking teen, the depiction never phased me, so I can't agree that smoking in movies advertises cigarettes, but particularly in old movies, smoking does at times look pretty cool. So far, the MPAA has not decided to accept the proposed PSAs, and they are reportedly investigating "anti-smoking alternatives," but if they were to break down and issue the warning to studios with a mandate to include them on DVDs (etc.), they might as well have PSAs that tell us not to use guns, commit adultery, eat fatty foods, drink alcohol, and many other things that could ruin our well-being. And instead of putting the warnings at the head of the movie, they should put them right before the credits, or during them, to tell us that what we've just seen is not good for us -- similar to when sitcoms had "very special episodes" accompanied by such messages.
The one thing I could suggest that might work is to have a PSA with a montage of all the famous actors and actresses who have died of lung or throat cancer. If they have video of the celebrities in their last days, that might work even better. Otherwise, we're likely to eventually become used to and ignore them just as we do with the anti-piracy warning.