This is the 4th time somebody has used this glitch against our group, We were trying to kill the glitcher during the day time on the same server so we flanked around the airfield to where he was then the server restarted. We then joined back and it was night time but by the time our group was loaded in the guy was already in the prone glitch yet again and killed all 3 of us.
(Video is kind of hard to see since for some reason screenshots and recording don't like to pick up the gamma changes but if you look closely you can see him sliding around prone)
Video link -- Here