Signed in the early hours of September 30, 1938, the Munich Pact allowed for the Nazi German occupation of Czechoslovakia’s Sudetanland -- an area along the border heavily settled by ethnic Germans. It was a peaceful way for Hitler to acquire more European territory without actually having to go to war.
The agreement was signed by Nazi Germany, France, Britain, and Italy, who did not want to fight over the land and hoped to appease Hitler by this deal. The Czech government was not involved in the negotiations.
Pictured here from left to right, just before the signing, are Neville Chamberlain of England, Édouard Daladier of France, Adolf Hitler for Germany, Benito Mussolini of Italy, and Gean Galeazzo Ciano, the Italian Minister of Foreign Affairs.
The narrator suggests that if the Czechs had not gone quietly along with the Munich agreement, but revolted as in the 1618 Defenestration, World War II would not have occurred. Given the character and goals of Hitler, this is a debatable conclusion.