Did you see the part with the SS men shaking the hands of the Soviets, while the captured Jewish children look on in horror?
I knew the Nazis collaorated with the Soviets but did not know of the broad extent. Also, they covered some of the gulag situation, but not to enough IMO. To be clear the Soviets were an equal opportunity murdering machine - everybody participated and everybody got murdered sooner or later. But there was plenty of racism and bigotry to go around in Stalin’s regime.
Obviously, Aleksandr Solzhenitsyn, Gulag Archipelago goes into great gory detail.