I've seen that man times, but not often. If memory serves me right that means your teammate is using a controllable Killstreak like Assault Drone or Remote Turret; they're firing at enemies with it.

I could be partly right or completely wrong.

Those lines around a player on the mini map is when said player is talking on his/her mic. This can even be generated by background noise picked up by the mic in the room in which the player is gaming. HD headsets are notorious for this, Turtle Beach , Tritton , Bose...etc.