The line comes from Half-Life 2, the 2004 first-person shooter from Valve, where Combine soldiers use short radio-filtered commands to coordinate attacks on the player. Take him down is one of those battlefield orders, and like many Half-Life 2 voice clips it was lifted into soundboards and gaming videos because it is instantly recognisable to players and needs no context to land. It survives because it gives any edit a clear villainous order and a moment of escalating conflict.