How do Trump’s Twitter taunts affect the presidency?

President Trump's Twitter attack on MSNBC hosts Mika Brzezinski and Joe Scarborough -- whom he called "low I.Q. crazy Mika" and "Psycho Joe" -- ignited a firestorm of sharp criticism, even from the president's Republican allies. John Yang reports and Judy Woodruff talks with Beverly Gage of Yale University and Matthews Dowd, former chief strategist under George Bush, about the implications.