That's quite an easy one to answer... first, do something you want to film; (campaign mission, firefight, etc.) then go into the theater lobby. There you can start to edit your clips, then you can share them in the File Share! Hope this helped!
you need a capture "device" (capture card)
Type in on you tube how to make halo reach race tracks
yes it will be HALO reach or ODST
if you are saying how do you make your own world in halo reach, use forge mode to make a map.
From the main menu just select "theater".
You have to go to theater mode (make sure there is only one person in the mode), then you hit 'X,' and hit the circle button.
you make a halo reach racetrack by putting alot of walls or something that a vehicle can fit on and put alot of twists and turns
They say that their will be a halo 4, which is the movie.
Improbable, since it cost more to make a film then it takes to make a game.
i do belive there will be a forge to make maps like Halo 3 did.
Delete it?
make him look like me!