In Czechoslovakia he ran afoul of both the Nazis and the Communists who subsequently replaced the Nazis in the postwar period, and spent seven years in prison and labor camps, four of them in a uranium mine labor camp. He was one of Czechosolvakia's leading Film and TV actors and writers when the Soviet tanks rolled into Prague. Valenta fled to Canada with his family, where he directed films for the National Film Board of Canada and appeared in numerous Canadian and European Films. He once said he had lived under six different political regimes "... and when you are a character, like me, and not a collaborator, you worry every day [no matter the regime]." He played Max the Stationmaster in the 1968 Oscar winning foreign film, Closely Watched Trains. In the 1970s he collaborated with Milos Forman and Ivan Passer in the Chelsea Hotel in New York. Valenta was the subject of a National Film Board documentary called Closely Watched Freedom directed by Tom Radford in 1993.