I'm in the process of applying for the Army Chaplain Candidate program. (This ordeal has hit some bumps; in fact, it has been a bumpy road from the start, so your prayers are greatly appreciated.)
On occasion, I find myself sitting across from a pastor that has no idea what a military chaplain does. I enjoy trying to explain what I know (although admittedly my knowledge is limited to my observations while I served in the Army, my reading, and my classes). This video paints a nice picture of some of the aspects of the chaplain's combat-zone mission. What it does not show is the chaplain's effort to visit and minister to soldiers in outlying areas (Forward Operation Bases, FOBs) or the garrison mission, that is, the mission on a post or fort. This video also neglects the chaplain's mission in military hospitals and the military prison duties.
In addition, here's a good interview with CH (LT) Anthony T. Carr by Timothy Dalrymple, titled "Finding God at Gitmo." Chaplain Carr is a chaplain is serving US sailors detailed with guarding detainees at Guantanamo Bay, Cuba. Although Carr says "no matter the location, my role as a chaplain would be the same: to provide spiritual support to the sailors around me," he has a unique opportunity to minister sailors facing problems unlike what their counterparts on ships might see.