how do i change the view from 1st person to 3rd person in halo custom edition?

[cody]

i saw a vid on youtube where the view changed from 1st to 3rd and i need to know how

 

[Lamadude64]

What I think you mean is a mode you can do in Halo 3, where you can watch and edit matches you've played and story missions. One of the camera views is from a third person perspective, so that is most probably what you saw, since i'm pretty sure Halo games can't be controlled directly from a third person perspective.