I know its mainly speculation, but that's what we often do when talking politics. I think Palin's release of her video, knowing that it would be picked up by all the major media, is another example of her great political instincts. She looked, sounded, reads like, a president, in that video. After I saw that video I realized it was an implied gauntlet left at the feet of one Mr. Obama. Would he look, in his speech, as presidential as Palin? or would he give a smarmy, partisan, Clintonian, blame-talk-radio speech? I propose that he planned the latter until he was told about Palin's speech. He coudn't afford to look less presidential than Mrs. Palin. So, the tone of his speech had to be changed. It isn't what his base expected, but he couldn't afford to play to his base after the Palin speech. It was like a great tactical chess move. She forced him to retreat and regroup. Without Obama leading the charge, the leftist commentators who still want to blame her sound like shrill harpies hanging out on a dead tree.
And as for the blood libel phrase. Robert Avrech, an Orthodox Jew and screenwriter, used it extensively to describe the attacks on Palin BEFORE she used it. See www.seraphicpress.com. It was completely appropriate.
By releasing her video on the day of Obama's speech, Palin changed the rules. Good for her.