Depending on the details I can't see from this video, and depending on if he gets proper medical care (lol), it could prove to be fatal. Warning, this paper includes medically graphic images: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7578127/
Technically, this is achieved with weapons simultaneously firing the grenade and ejecting a similarly heavy mass at a similar speed opposite the direction of fire...
here specifically, good question, he can still move legs so spine is probably mostly intact, but i'd guess there's some nasty TBI and blown eardrums or at least one