There is no need to watch this video because there is all kinds of testimony to the fact that this happened, and Auschwitz wasn't even the worst of them because it was actually attached to a work camp whereas there were other camps where people were essentially gassed immediately, such as Sobibor. There is an episode in the World At War series in which a Jewish person describes literally taking people out of the gas chambers and putting them into the ovens on a mass scale, as well as that of a German officer who witnessed the the same.