“I want to understand the complete mechanics of World War I and II. What was the reason for the wars, what was involved and the aftermath.”
Beware, for thou hast summoned a WW2 geek…
Really, you need to watch many documentaries and read many books to get all this. Hollywood movies just ain’t gonna do it, for they are stories usually told with carloads of creative license in order to make boatloads of money (I’m looking at you, Pearl Harbor and U-571!). And even Downfall, as great as it was, only covers the very end of WW2 from the German perspective.
The absolute best documentary series in terms of technical accuracy, scope and objectivity in my opinion was the first and second series of Battlefield (series three does an excellent job covering Vietnam, series five and six are rubbish rehashes of the first two). A very close runner-up is the older but more widely-known and respected The World at War.
Battlefield is now virtually unobtainable, especially for some episodes from series two. For those interested, PM me and I can give hints regarding ways around this. ;)