It has been more or less confirmed that the guy is a Marine. His name is known and he’s now bearing the brunt of an internet-generated shitstorm.
However, I think the dog was either fake or already dead. The noises are highly suspect. Not only the yelping, but the thud you hear when the dog lands. There is no way in hell a consumer-grade camera would pick up the sound of a dog that size landing at the bottom of a cliff 20 yards away.
It has been confirmed that Motari is a Marine. Whether or not that is actually him in the film has yet TBD.