User "mengutimur" has put the whole BBC 1964 "The Great War" on YouTube.
Way, way, way better than newer series, which I find too gung-ho "Brits rock, Germans suck, we were right, they were proto-Nazis and the Kaiser was evöl" type of pop documentaries.
I find the old one way more nuanced and balanced. Plus they actually had veterans of WWI, still rather young.
http://www.youtube.com/watch?v=oBrD_u20UF0
An absolute must see, up with The World at War for WWII.