I just found this group a few months back. What most people don't realize is that they have probably already heard at least one Two Steps From Hell in the past decade, and wondered "wow that was cool, wish I could get that soundtrack."
So what do they do specifically? They are part of a niche corner of symphonic music known as "trailer music." No, we're not talking wife beaters or trailer parks. Let me show you couple examples:
And their associative music:
They also do some stuff that hasn't been attached to trailers yet but is so fun and catchy that they have to be played... just one example:
I post this thread not to create yet ANOTHER "what is your favorite (band/song/style/track/etc)" thread. This is simply a PSA that most of the music in trailers that you like IS available and IS out there. You just have to find it. Other acts that do some music include Immediate Music and their associative act Globus, X-Ray Dog, and a few others.