Well, I know what all of them are. I don't know how, but I can explain what he did. Note, I will explain these in simple terms, not the technical way. :p
Golden Deagle: He took the Call of Duty 4 Image for the Gold Deagle and replaced it over the MW2 one.
Wall Hack: Implemented the AC-130 interface into regular gameplay.
God Mode & Unlimited Ammo: He somehow binded them to keys, obviously via Jtag.
Unlimited AC130 is a result of unlimited ammo.
AC130 at the beginning of the match: He binded an AC130 to his controller keys, most likely using a code like this: ".bind DPAD_UP GIVE_MP_AC130"
Firing with his hands: That is a dev gun made by IW back in CoD2 and implemented into the game engines ever since. It has been in CoD2, CoD4, Co

WaW, and now, MW2. Basically it is there to test certain basic features of guns, it is also a one hit kill gun in regular, and obviously hard core.