[2:14] - Straight to the Top COG Tag
After dealing with the Snipers, you'll find a large hole in the ground inside the building. Drop down the into the hole, head straight into the office room, and then mount through the windows on the right hand side. After going through the windows, turn left to find the COG Tag.
This one is also very missable as I missed it twice. You're definitely not forced to go down into the hole as you state in the video. You can open the door on the floor above the hole and completely miss the tag below.