While I agree with Matthews on the Welfare ad, I don't believe Romney was playing the race card with the Michigan/birther comment. It struck me as an off the cuff, awkward attempt at snobby humor from someone who seems almost incapable of being funny.
I don't even have a tv but see or hear the welfare ad nearly daily. It's played on various online streaming sites like Hulu, and at work it's often a commercial on Pandora. It's a very potent ad, but is so matter-of-fact that it's easy to debunk. Luckily many in the media are doing that, and I'd imagine many people are looking up the ad/facts online. Still, it's the type of ad that makes more than a few people say "aha, I knew it all along"