One: Start a four player FFA. Two: Disconnect and die. Three: Reconnect and be most very annoyed that you can't change your vision from yourself to everyone. Four: Still be annoyed after the game ends because you still can't change your vision from yourself to everyone. :\
Yeah I've noticed if you die in a game and become a spectator you don't usually get full vision. I thought this was due to being in a team (therefore not being able to give anything away to your surviving team mate) however apparently it still applies in FFA games?