Several of the scenes in this move have been restored in Peter Jacksons "They Shall Not Grow Old". If you haven't seen it, well worth watching - and having this un-restored version to compare to makes his movie all the more impressive.
https://www.justwatch.com/us/movie/they-shall-not-grow-old
It, in my opinion, has set an amazing standard for any future WW1 documentaries to attain.
Ordered! The Challenge of the Dead: A Vision of the War and the Life, of the Common Soldier in France, Seen Two Years Afterwards Between, August and November (Classic Reprint) https://www.amazon.co.uk/dp/B008R51UKO
Actually when I looked at my bookshelf I realized:
Buy this book for your friend, they will thank you forever:
https://www.amazon.com/First-World-War-John-Keegan/dp/0375700455