YouTube turned ten years old this month. That's old! It's frankly hard to imagine a time when we didn't have the massive video platform in our lives. The world has changed a lot in the past decade. Ten years ago, YouTube was just a guy visiting the zoo. Now it's a gigantic Google-owned driving force in pop culture. YouTube has been looking back all month on its ten year history, doing an A to Z of all the types of videos that appear on the platform. To wrap things up, they've created this celebration video. See how many YouTube heavy hitters you recognize in this "Alphabet Aerobics" video.