On February 12, 2009 the third Halo Wars ViDoc was released. It describes the controls featured and what expectation there are of the game. Like the previous ViDocs, this one features cinematic scenes.
At a certain point in the video, exactly three Brute Chieftains, one Arbiter and six Elite Honor Guards are shown fighting against a UNSC army. This would mean that all three Covenant leaders would have had to of been selected to get all these things at once. And it is strange that there are so many Brute Chieftains when it has been thought that you could only select one in a battle, this could mean that there is the main Chieftain, and the more lesser unnamed Brute commanders, or that the image seen is from a multiplayer match where multiple players are playing as the Brute led Covenant faction. However this is unlikely, because there is an Arbiter and six Honor Guard Elites being shown. And it has been thought that you can only have 3 players on one team (A.I. or non A.I.).
It should be noted that this ViDoc lasts for 3:43 minutes, this is possibly a reference to 343 Guilty Spark.