Thats not a FPV drone in the picture its a spotter drone
there isnt enough bandwith in the 5.8GHZ analog video band to have 19 drones in the air at once (u can do 8 at best). Even less if u use digtal VTX on 5.8GHz. And dont get me started on 2.4GHz analog.
This means ita very unlikely to be such a amount of operators at once. It could have been 4 Operators tho that did send 19 drones in rapid succesion.