The Bruins (2-0) trailed 2-0 late in the second period before coming back. Camper's goal, in the eighth round, ended the game.
It was the second time in three years the Capitals played a preseason game in Baltimore. A pane of glass fell and broke on the ice after Washington's Alex Ovechkin and Boston defenseman Chris Castro collided in the corner with 4 minutes left in the second.
Both teams skated off, and the final 4 minutes were played immediately before the third period.