Just remember both people involved in this exchange are being paid by CNN. What you're watching is nothing short of a shitty professional wrestling promo.
CNN or not though, I can't think of another time when a lefty just cracked on air, at least not in a movie. Or comedy news I suppose. But anyway the closest I've seen in recent memory on a "News" News Program was when Judy Woodruff kinda forgot she was on the air for a minute during election night and the correspondent she was talking to kinda had to abruptly change the subject. I mean, Cooper's utterance is no surprise, but I'm still kinda surprised it was let happen, since that'd beg the question "why didn't CNN start doing this 20 years ago when Fox started doing it to them?"