This is an iconic scene from the 1939 film Grand Illusion.
The title of the film comes from a book—The Great Illusion by British economist Norman Angell—which argued that war is futile because of the common economic interests of all European nations. The perspective of the film is generously humanistic to its characters of various nationalities. It is regarded by critics and film historians as one of the masterpieces of French cinema and among the greatest films ever made.In the embedded video, a group of WWI French soldiers in a German P.O.W. camp are performing a series of skits when news arrives that a French town previously captured by the Germans has been retaken by the French. (The embed has low resolution which reflects poorly on the film [and an unskippable ad], but I couldn't find a better copy of this scene on the 'net this morning; for a better sense of the film as a whole, see this trailer. Or - even better - this review of the movie.)
When I watched the movie last night, there were two striking episodes. In one, the POWs dispose of dirt from an escape tunnel by sneaking it inside their clothes to the courtyard, where they dump it in a "garden" they are tilling - a scene that was clearly borrowed during the making of The Great Escape.
I wanted to blog the scene above because of its striking (and probably even more famous) reprise in Casablanca:
And a final bit of trivia for true movie buffs: one of the stars of Grand Illusion was Marcel Dalio, who played the part of the wealthy Rosenthal. He was also in Casablanca (as the croupier).