If you get all of the vidmaster achievements bungie say you will get something special in the game.
In this video we will show the location of the ghosts on the final level "halo" in halo 3. We will also give you all some tips for getting through the level on legendary with the iron skull on. It's not really a hard or difficult achievement but it will take time.
More tutorials will come for the new halo achievements in the next few weeks.