His accent isn't really Southern ; if anything, he sounds Northeastern. The only word he pronounces with a southern accent is “influence”. My guess is that he's either toning down his accent for the camera, or he's from a larger town like Memphis, Nashville, or Knoxville.
I remember a Sgt from the CRAPS (GCP) with 10 years service, Danish or Dutch, being interviewed in French. They put the subtitles of what he was saying in French. Needless to say he was taken the Micky out of by the other sous-officiers, like, "can't understand you, were are the subtitles?"
It's a bad luck when they put subtitles on your speech, especially when you speaking in your native tongue.
Sometime they do that completely unnecessary, someone have lil bit of some foreign or English accent an they put subs on him, it’s a bit frustrating sometimes. (especially for subtitled person ). That guy from Tennessee speaks perfectly understandable, no need for title.
I also hate when they do translations of someone's non-English speech and do that with heavy accent of nationality that person belong. That's really, unprofessional, childish and sounds ridiculous. It's like they want to mock that person, which would be OK if they do because sometimes those translations sound really funny. Problem is they do that unintentionally. Probably in need for their translations to sound more realistic.