I could speculate on any number of reasons. A large number of my relatives work in defense contracting and you see the same videos passed around there as well. I admit that I feel slightly unnerved by the videos sometimes, but if you're an engineer working on gunships or a former soldier for whom this was a part of daily life for a while, I don't think there's anything really blameworthy in finding videos from the war interesting on some level.
It's just interesting, that's all. For me personally, seeing people killed on the battlefield isn't a good feeling, but it's not strange either. It's not outside the sphere of my experience. I know that people get killed in war and sometimes it's tragic but it's still interesting to watch firefights and gunships engaging targets.