There are several sets that need to be made for each character, each set corresponds to the current mood of the npc towards the player, there are also transitions from one mood to another, for example if you are talking to a NPC who is neutral towards you and you insult them you will see there mood change to an angry face.
This Tutorial only deals with the art aspect of the process. To use talking heads in game you need the artwork, the audio files and the Lip sync files, then the heads need to be scripted into the game.
