Call of Duty: Black Ops 2 is a big game, at least in terms of its multiplayer offerings. It's huge, complex, and with its size comes exploits and glitches that players who've spent tens of millions of man hours have discovered that no QA tester at Activision or Treyarch could ever hope to find.
The latest of these exploits is a glitch that allows players to make themselves invincible. A veritable god mode, in other words.
The god mode glitch, as it's called, can be seen in action in the video below, recorded by FullAhBeans as proof of its existence.
According to the player, he was playing on the map Downhill. He was doing fairly well—pubstomping, as it were—when the host migrated. Shortly after the host migrated, the player checked his party status and found that he was both "not in the game" and "in the game" at the same time. What happens after that is anyone's guess—he is able to walk around in the map, and players are able to see him, but he's unable to interact with anyone, nor can he be shot by anyone. Essentially, he's become something of a ghost.
It's an odd bug, and while it doesn't allow you to really exploit, it does throw you out of the action and break the game.
With any luck, someone from Treyarch will figure out what's caused it and fix it in due time.