Pelosi: Trump's public attacks on witnesses are "very significant"

House Speaker Nancy Pelosi on Friday slammed President Trump for his public attacks on witnesses, including former U.S. Ambassador to Ukraine Marie Yovanovitch. "He should not frivolously throw out insults, but that's what he does. I think part of it is his own insecurity as an imposter," Pelosi told CBS News' Margaret Brennan in a wide-ranging interview.