What does that mean for Halo 3?

[Lil Ay]

"If you are playing alone on the Legendary difficulty setting, turn on an idle second player to stay behind. If you die, you will respawn instead of restarting."

What does that mean??

I need this because im having trouble in legendary with this wraith with tuns of brutes. and it is ****ing me offfffff!!!!!!! (its when i have to go to the city of Vio).
Since there is no infinite health i have this cheat so i wont lose my spot. i found a cheat (its the one up top) but i dont understand what it means. PLEASE HELP!! Thanks.
Oh i mean the part when it says "idle second player" mean? what does that mean?IM lost with that part.

 

[xzorion54]

If thought if any player died during co-op on legendary both players would get sent back to the last checkpoint no matter what, or was that with the Iron skull activated?

Anyways, the "cheat" just tells you to play the campaign in co-op mode with the "fake" player just staying behind while you go around killing things. Apparently if you die while you're out there instead of getting sent back to the last checkpoint you'd respawn next to your "fake" player 2 to go kill again.