Even fewer people are aware of the truth who financed the bloodthirsty Communist takeover of Russia in 1917,Nazi takeover of Germany in 1933 and buildup of Nazi war machine to make this gruesome history possible.
I don't believe documentary about this will ever be made. The answer could be found only in dusty books. "Follow the money" and "Follow the works of art" is the best lead.
So cryptic! ;-) Which works of art?