As a musician, nay even a composer of music, I wonder how I've managed to get by so long never having even heard of dark music.
Okay,. so then I clicked on the OP's link to the segment of Batman theme and listened for a bit. Then I did a search at YouTube on the term 'dark music' which revealed a large number of hits, several of which I listened to. Geez, a genre, and one that I wasn't even aware of.
Look, to me, most of the dark music I listened to just now could be most usefully described as 'dynamic soundtrack, where bass registers predominate, often with a strong, marshal-like beat.' I emphasize soundtrack because this is the area -- or arena -- where music like this is most often successfully employed.
Now having written the above, and again, writing this as a composer, just let me say that this is also a type of music that I am very interested in adding to my skill set. Not just because I enjoy it, but because writing effective, dynamic musical scores can be a nice, fun way to make a very good living.