Ezra Klein gets a little obssessed with the headbutting video.

What’s more, take a look (as you did the JFK assassination video) at Materazzi’s head. What I would expect–after a frontal assault on his chest–is for his body to move backwards and for his extremities to compensate (momentum conservation for you science folks) by lurching forwards. What’s more, you’d expect the severity of the lurch to correspond to the severity of the initial insult. And indeed, you can see but the tiniest eensiest bit of forward Italian head motion before it, out of nowhere, FLINGS back wildly and Materazzi’s entire body crashes to the floor. That means there was an invisible headbutter, or that the dude was acting in accordance with the way the Italians played roughly all World Cup: skeezily.