'The Great War' is a project of film archive British Pathé, shows you the history of the First World War in the four years week by week from 1914 to 1918, exactly 100 years ago.
The videos are available in three languages, English, German and Polish.

Enlgish: https://www.youtube.com/user/TheGreatWar
German: https://www.youtube.com/user/ErsterWeltkrieg
Polish: https://www.youtube.com/user/WojnaNieznana

Also check out The Great War documentary by BBC in 1964 if you would like to watch more WWI videos.
https://www.youtube.com/channel/UCNQea435qSQ4SMCsDthXHfg