Location is at the entrance to the Iron Banner area. At around a -45 degree angle on the Y-axis of the player's view, the shadows from the light beyond the closed gate flutters while walking. Jumping while looking -45 to a possible +45 degrees also causes this. If looking further down towards the ground, everything is fine. In case the video does not show, here is a YouTube link: https://www.youtube.com/watch?v=kPYPeot9bs0#t=11