Recycled Content is when a newer game in a franchise uses assets from older games from the same franchise or from the same developer. Now let me put you in to perspective of what i mean by that in black ops 2.
Black Ops 2 has a whole shit load of Recycled Content in the form of it's texture for guns ext. mostly reused from the older Modern Warfare games such as MW2 and COD4
MW2 Black Ops 2
As you can see all of those are super similar or almost exactly the same. The only differences are the colours but the basic model is the same. There are are several other examples such as the Peacekeeper which is a gun from MW2 called M208 as well and it hasn't even been retextured just renamed.
Another example of Recycled Content is the statue in the middle of standoff which was copy pasted from COD4. Thats all for now don't wanna get too pissed by this ill see perhaps another time to show you some more screenshots of what i mean but man its just so fucking retarded.