Bill Hader’s rise to stardom began behind the scenes on movies and TV sets, before he took an improv class and quickly made the leap to “Saturday Night Live.” In this week’s “Sunday Sitdown,” Willie Geist talks to the actor and comedian about what he calls his journey from "preschool to Harvard,” his Emmy-winning HBO series “Barry,” and his lifelong dream to meet the subject of his most famous impression: “Dateline” correspondent Keith Morrison.