2011 Denali DVD hard drive video format.

[Enoob]

I am a new purchaser of an 11 Denali and interested in how to use the USB port to play videos (only has 2nd row DVD, no rear). I have only located a few posts on this and they were not real specific as to options. One referenced that in the 11 model, this may not work. I have not taken possession of the vehicle yet so I am unable to test it. I will be obtaining it soon and have a long road trip to get it home. Interested in taking a video collection for the kids. What experience does anyone have with this particular model year and the formats needed to play videos? Are there more than one model of head unit? Also interested in using something like a portable hard drive with Wi-fi (to auto-sync with my home) as an option, or simply a hard drive for a larger video collection over a USB stick. Would this model year's head unit have the extra USB port on the rear so that another port could be wired up front, rather than relying on the center console? I have used Handbreak to rip files so am familiar with that process some. Thanks in advance!