LOS ANGELES (Reuters) - Christopher Plummer won his first Oscar on Sunday for his supporting role in "Beginners," in which he plays an elderly man who comes out of the closet and embraces his gay identity. Plummer, 82, a veteran screen and stage star best known as Captain von Trapp in "The Sound of Music," became the oldest person to receive an Oscar in the history of the Academy Awards. That title had previously been held by "Driving Miss Daisy" star Jessica Tandy, who won an Oscar at the age of 80. ...