I can't remember if I've mentioned this before, or seen it mentioned...
The BBC iPlayer has a selection of video clips from the 1960s- archive recollections of survivors of World War I. Most are 20-30 minutes long.
The clips were done for the Imperial War Museum, which I believe has many more- the BBC is showing 13. They include Cecil Lewis, author of
Sagittarius Rising, describing aerial reconnaissance and combat; Horace Birks, a tank commander who went on to command an armoured division in WWII and Charles Carrington, a teenage platoon commander on the Somme who was leading a company by the time he was 20.
For those outside the UK, you'll probably need a VPN to pretend to be in the country, then go to
www.bbc.co.uk, click the tab for iPlayer, then Categories, then History, then the alphabetical listing for The Great War.
Plans are afoot to make the iPlayer chargeable for anyone who does not have a UK TV licence, so I can recommend having a loom soon.