I went back and watched the video. I would say the kick dropped him. He even cringed and leaned forward, into the kick. A likely oh shxx moment.
This leads me to believe that hitting dudes in full armor with blunt swords, doesn't do much damage so it's basically high $$$$ Larping, But the kick, is real blunt force trauma, and this is the case of Larper meets Larper/Fighter....and the Larper folded under real pain.