The game is shown in this video, for example, from 6:04 to approximately 7:40.
This is For Honor, a game released in February 2017. Could be kinda easily mistaken for Chivalry, but there are some distinct differences (e.g. Chivalry doesn't have NPCs that actively participate in combat and fight, combat system is a bit different, etc.).
This is - Chivalry: Medieval Warfare