Because union rules require a unique name, added Seymour, which was his grandfather's name, to his stage name.
While in high school, he played Radar in M*A*S*H and Willy Loman in Death of a Salesman, a role he eventually played on Broadway in 2012.
Between junior and senior years in high school, attended a Saratoga Springs (NY) drama camp, where he met and became friends with Bennett Miller and Dan Futterman, the director and screenwriter, respectively, for Capote (2005).
Breakthrough role was as film technician Scotty who carries a torch for porn star Dirk Diggler in 1997's Boogie Nights.