Samuel Fuller and The Big Red One (1984)
https://www.youtube.com/watch?v=srVJsCRJJLc - from the Thys Ockersen YouTube channel (1 hr. 16 mins.)
The blurb (from IMDb):
“A documentary chronicling the filming of Samuel Fuller’s 1980 war film, ‘The Big Red One’. Included are clips from the film and interviews with the cast and crew.”
I really like the “Reconstruction” cut of The Big Red One. It’s one of the very few times I’ve seen a good movie turn into a great one by adding a few key scenes back in.