Bullshit.

The downfall of the Nazis was because they attacked Russia but were in no way prepared for the Russian winter. Where many soldiers simply froze to death (one must not forget meth or Panzerschokolade). This means that soldiers who are overtired do not realize that when they are tired, the body no longer works at 100%, making it more susceptible to cold and producing less heat). This mass death from the cold gave the USSR the opportunity not to be overrun and to push back the Nazis. Had it not been for the winter, the USSR would have fallen. America would have had an enemy over a much larger area (this was all before the Americans were able to seize all the knowledge of the Germans), the Germans were already close to completing the atomic bomb... as well as stealth airplanes etc. Believe me, if so many had not frozen to death in the East (fortunately) it would all have ended very differently.