Actually, because the thought of color photographs of that era intrigued me, I used my google-fu and came up with the following things. First, apparently the BBC has no plans for release of that and other related Alfred Kahn documentaries, due to some sort of copyright issues. However, they are releasing
this book in the spring (which I have pre-ordered).
I also found
this site, which details Kahn's ambitous project to record the whole world in color photography in the early part of the 20th century, which has a link to
this site, which has hundreds of autochromes taken by the French during the last two years of WWI.
I agree with
glyn, seeing color pictures of an era we always think of in monochrome is quite amazing.