One of my all time favorites... As a history buff, I found a satirical musical history of WWI to be delicious. The songs are memorable, sing-along-able, and the acting by that incredible cast is, naturally, incredible.
It does help to know the real history of the period...the symbolism of the red poppy, the obscene politics of the period, the insanely bad judgement of generals, war ministers, just about everyone involved in the "running" of the war. But if you do have some knowledge to work with, the movie says it in music better than anyone, except maybe Barbara Tuchman in "The Guns of August"...
It does not appear to be available on videotape ANYWHERE. I have not been able to locate it at any price. If ANYONE knows where I could get a copy of this grand movie, please contact me!