You need not delve too much into the MSM narrative nor what Nazis are. We're all familiar. (Though it's worth pointing out that the Holocaust was not mainstreamed until the 1970s.)

However you'll want to clearly and concisely explain that propaganda and demonization makes the underdogs into sub-human 2D evil villains, when in reality everyone has substantially valid viewpoints. Easy enough to gather examples from history up to the modern day. Also easy: make the USA and the West the bad guy bully. For academic validity I'd use the words of the "leaders" of the age, before WWII that laid out their plans and goals that all came to pass. It was a manufactured event, planned from the 1800's.

IMO, to deal with the "witnesses", simply present them exaggerating and lying with their own words. There's way more than enough to select a compelling best of the best.