Step one pick your USB as your storage device
On mw3

Then go to private match (optional)(or a online game)


Then get the video from horizon <---(pc)---- and then drag it into hxd then search (find)
-example-
Mp_whatever map you played on
Ex mp_dome

Then if you want to change the map just change dome to what ever you want then
If you go up a little you can see a paragraph of jibberrish and at the end of it
The game type code here are some
FFA
Dm
Search and destroy
Sd
TDM
War

Ok so before the those 2-3 letters you can start writing whatever you want that's the description

If you go down more past the mp_
You can find your gamer tag you can change that to what ever in colors and it can be up to 20 characters long

Color codes for dummies
^1-red
^2-green
^3-yellow
^4-blue
^5-cyan
^6-pink
^7- white (default)
^0-black
^: (Pale Blue) and ^; (Pale Yellow (Flashes Once)