The video: Elizabeth Warren, the polarizing consumer advocate who's challenging Republican Sen. Scott Brown for the Massachusetts Senate seat Ted Kennedy held for nearly five decades, is already whipping up excitement on the Left. After announcing her candidacy last week, Warren has already surprisingly overtaken Brown in one poll. And now, Warren has gone viral with a "kick-ass" living room speech ridiculing critics of President Obama's proposed tax hike on the wealthiest Americans. (Watch the clip below.) Warren scoffs at the idea that Obama is engaging in "class warfare," and argues that "nobody in this country got rich on his own." "You built a factory and turned it into something terrific?" Warren says. "Keep a big hunk it. But part of the underlying social contract is you take a hunk of that and pay forward for the next kid who comes along."

The reaction: "Watch out, Scott Brown," says Colby Hall at Mediaite, Elizabeth Warren is clearly "touching a nerve." Indeed, says Steve Benen at Washington Monthly, this two-minute clip demonstrates why Warren has such passionate supporters, and should silence any doubt over her ability to deliver a rousing stump speech. "First-time candidates don't usually articulate a progressive economic message quite this well." Actually, says Howard Portnoy at Hot Air, the speech "is a gift to Scott Brown." The government-provided services Warren trumpets — like schools and cops — "no more determine the success of a rich entrepreneur" than they do the poverty of 1 in 6 Americans. Now Brown can easily paint Warren as a "moron." Judge for yourself: