If you watch the video there is no doubt
1) he’s an american
2) he’s not military (haircut)
It turns out some of the koreans are saying “NI-GA”, which is part of ordinary korean speech (means “you”) and meant innocently.
The man in the video interpreted this to mean they were using an epithet when they weren’t so he attacked.
That’s no excuse for savaging an old man and acting like this in a foreign country, but it helps to understand what is going on.
Just goes to prove:
1) When going to someplace unfamiliar to you, it pays to do a bit of studying ahead of time, language being high on the list.
2) A chip on one's shoulder doesn't do anyone any good.
You don’t think some Koreans haven’t made the sonic connection between “ni-ga” and” Ni—er”? They probably think it’s funny!