Well, any success in swaying voters is bound to be minimal. I was watching a news report this morning, where two female democrat and republican politicians based in Denver, were discussing the upcoming elections. They both agreed that swing voters tend to pay more attention to negative advertising, recognising that its unfortunate that their is so much of it, but that it appears to work, as people don't like the thought of bad things happening. Suggesting that a vote for the opposition will lead to said bad things, garners support for the party which the ads support.
In Michael Moore's case, i think perhaps he is taking the mickey to an extent, whereby a lot as been heard from the right, about how bad things could get if Obama gets a second term. The video suggests these negative repurcussions, none of which would actually happen, as a way of countering the scaremongerers i guess. In reality its just humour, appreciated by those already decided to vote democrats. Its not going to have a huge impact on swing votes, but it could just a little. People do enjoy humour afterall.
I am probably wrong in regards to my initial post however. Its probably not for the undecided's benefit at all, just leftist fun-making.