The crossbow is one of the weapons that is left largely untouched in PLAYERUNKNOWN'S BATTLEGROUNDS. It takes a certain amount of skill and luck to land a shot let alone from a distance. This player, however, manages to do knock an opponent when all the odds were stacked against them.
Considering all the factors that are affecting this shot, it becomes even more impressive. Normally when players attempt to snipe opponents they will equip a scope of some kind. Whether it be a 6x or even a 3x, increased accuracy is crucial. Unfortunately, the player seems to only have a red dot.
This players' weapon of choice is the crossbow. The reason why the crossbow is one of the least used weapons in the game is the difficulty of landing a shot is much higher than any other gun due to how a bolt acts after being shot. When aiming, players must aim much higher than they would if they were shooting a gun due to the speed at which the bolt is being shot is much slower than that of a gun.
After taking all these factors into consideration, the target is also moving around. So at a distance of 212m, Andydontcare fires his crossbow, with a red dot at a moving target and still knocks the player. The target was probably very surprised when they were instantly knocked, especially seeing that it was from a crossbow.