"Mad Men": Good to know

We're getting stoked for the season finale of "Mad Men" around here — not that I have to wait a moment longer to watch it, AMC sent me a screener, but I'm putting off watching it as long as possible because then it'll be over.

Anyway, they've got a pile of videos over at the website about the show.  In this one, Matthew Weiner (show creator) gives a surprising answer to the question: Do they actually smoke those cigarettes all day long on the set?