Awesome! And it does work!
First of all I would like to say that the individual who wrote, "Installation Failed" was blowing smoke the DLC does works! He or she may have installed it in the wrong place, does not have the requirements or just did not take the time to look up how to do it! Download/Install the DLC, Start up the game and entering the First Game Menu, Select "Extras"... From the "Extras" menu select "Exclusive Content" At the bottom right of the Exclusive Content menu select "Redeem Code" and enter the 19 digit code supplied with the DLC, if all goes well you should have 4 more Deniable Ops to play, Hope this helps out anyone who has failed the attempt to play the DLC, I don't want to spoil anything so the rest is up to you! Happy Gaming!