But did it?
Question: suppose you watch the Bain video and are horrified by the practices of private equity. You want to cast a vote to ensure that such practices are stamped out. Whom should you vote for? Answer: flip a coin. There is nothing in the Obama platform that will in any way protect workers from future depredations by future private equity investors. (And in fact, the actual Romney did much of his depredating under the last Democratic administration.)
The Bain attack ad is pure expressive/symbolic politics: vote Obama because Romney is a bad guy, not because an Obama administration will make any practical difference to people like those featured in the video.
Obama wants credit for being more caring, compassionate, and concerned than Romney. But even if that were all true (and I'm not at all sure it is)—so what? It's not like he has in mind any plan or policy actually to do anything very different from his rival on this score, other perhaps than provide somewhat more generous federal benefits after the plant is closed down.