Rick Astley’s “Never Gonna Give You Up” hit a milestone last summer—the YouTube video surpassed one billion views. That’s rare for any YouTube video, and taking into consideration that this is Rick Astley’s ‘80s-style music video, it’s especially surprising. Why are so many people still watching it? Thank the “Rickroll." Don Caldwell, editor-in-chief of KnowYourMeme.com, explains. (Segment produced by Sydney Jezik) (Photo Credit: Joel Ryan/Invision/Ap)