Mission 6 (Magazzeno Facility)
At the beginning of the mission, go straight ahead and look for the spotter that carries the flare gun you need.
Make it to the spot in the video and try to stay undetected or the enemies will leave their positions. If you are at the spot North-West on the map, you should find 5+ ememies standing right next to each other.
Take out our flare gun and shot it
right in the middle of the group.