I read the book ages ago. It mustve been when it first came out. I didnt know there was also a documentary on it and i looks to have been banned from youtube.
Having googled the guy that made the doc he's involved in white nationalist/separatist stuff, so that'll be why. The book seems well reviewed though, so I don't know if the doc just piggybacked on the name and some of the factual stuff about what did happen to many German/east european civilians at the hands of the Soviets and throws in some Nazi revisionism.