Can someone please tell me what's the name of the song from the Act 1 in Rogue Encampment?

If you don't know how it sounds like you have the following link:

http://www.youtube.com/watch?v=OTLodxEfdOA

You've linked to the theme from A3 Kurast Docks.

It's a nice song, as is the one chosen for Lut Golain, sorry I don't know the name.

Consider inquiring with "Mathematics" (aka Trevor) in the Aftermath mod forum. I think when that mod's origin initially splintered off from HU, they didn't have this song. When Trevor took over, he may have tried to include it, so might have it's name available.