CNET: When Stephen Colbert saw Donald Trump announcing his presidential candidacy, he surely thought: “I have to, don’t I? I just have to.” So he prepared a YouTube video to announce that Donald Trump has announced. Standing on a podium that featured the slogan: “Colbert. Shut Up, Dummy,” Colbert evinced a gravitas that reflected the seriousness of this moment in history. He admitted, though, that there’s a secret motive in announcing Trump’s announcement. Colbert is about to begin hosting “The Late Show” on CBS in September.