If a surprise guest is going to crash your YouTube video, you’d be hard-pressed to find someone better than former President Barack Obama.
Fred and Tim Williams, the YouTube sensation known as TwinsthenewTrend, who react to classic music, got just that treat. The 22-year-olds were reacting and discussing the Bob Dylan track “The Times They Are A-Changin” — which Obama included on his recent playlist tied to his book release — when Obama himself showed up.
“Hey people, what’s going…