Dying Light HOW TO FIND THE 9MM PISTOL
Early on in the game after you completed the introduction you can find many spots in the world where you can shock zombies using water on the streets. The spot in the video is near your homebase where you start out.
Make sure you have some spare firecrackers and lure them to the water. Once they are close throw the firecrackers and make sure at least 5 zombies are standing directly in the water. Pull the switch and watch them dance.