This guy was invincible. Clearly using some kind of hacks. I'm not the hacker so I couldn't really tell you how he was doing it. But this kind of stuff ruins the entire server.
Originally I was shooting from further away.. noticing that he wasn't taking damage or I was missing every shot I started recording. Here's the link.
Yes, and the fact that someone can make themselves invincible is a bug. Whether it be in the game or in the anti cheat engine a bug is a bug.
You're new to ArmA, aren't you?
Have you even looked for previous issues about hackers? I counted at least 10.
No use reporting any specific instances of hacking, especially since there is no anti-cheat implemented yet.