Latest dev build here. I've seen this exact same problem as a red ray coming from a dead teammate today in a singleplayer infantry scenario. It faded away after a little while.

I'm running a 2600K @ 3.4ghz. No overclocks. GTX Titan 6GB with a customized fan profile keeping the card at a peak of a cool 62 degrees while playing Arma 3. 16GB of RAM. CPU is hydro cooled reaching the mid 40s at peak. MB temp reported at 28 degrees. Heat is not an issue with my rig at all. I'm running the latest drivers. I also use SSD drives for the entire system.

I haven't played much recently but I would say this one is hard to reproduce. Very random.