The digs against Bush -- that he's stupid, inarticulate, and cartoonishly belligerent -- are old news. They've been repeated for years and get repeated several more times in the animation, but they're not delivering any new information or swaying any undecideds here. Bush is a known quantity, in real life and charicature.
Kerry is less well-known. The digs against Kerry deliver novel negative characterizations to a new and receptive audience. Kerry is shown as haughty, vain, super-rich, and mocking of poor people. (While Bush only misspells Massachusetts, Kerry sneers at an image of poor life.) Kerry can't shut up about his medals. And two meaty points the GOP would like at the top of voters' minds -- Bush delivers tax breaks, Kerry flip-flops on issues -- get prominent airing. (None of Kerry's substantive talking points, such as they might be, get similar placement.)
The same imbalance is evident in the visual parodies. Portrayals of Bush as a cowboy, a tank driver, and wearing camo fatigues aren't so bad for a war president who can benefit from a macho image. There's no such silver lining for Kerry being portrayed as a ketchup-pushing hot dog, Herman Munster, U.N. sex slave, diapered baby, funky peacenik, or botox patient.
JibJab's "This Land" is hilariously clever: a great mesh of visuals, words, music, and voices. (Did one guy really do all the voices? Wow.) Its veneer of equal mockery, and the final scene where Bush and Kerry join arms, add to its charm.
But point-by-point, it's a really effective piece of pro-Bush propaganda -- even if it wasn't consciously designed that way.