How do you get down the hill on the campaign level, SOG?

In Call of Duty: Black Ops, on the mission SOG (Vietnam), you come to a point where your orders are to push back the NVA down the hill. I've spent a lot of time slowly pushing down the hill but the enemies keep coming and on Veteran difficulty at some point I always end up dying. My squad mates pretty much stop at the first level down the hill providing no help.

I'm sure a portion of it is skill, but there must be something I'm missing to trigger my squad mates to continue on down and move the level forward and stop the enemy from spawning. Any ideas?

Some of them will come at you regularly and some of them will not reveal themselves until you have reached a certain spot, so keep moving, but take it slowly.

Going kamikaze on veteran means certain death.

As soon as you clear all positions, they stop spawning.

You can roll barrels burning (just knife them by pressing "use" key) and use the machine gun at the side to make things easier.

You do kick the barrels. Get close enough and an action prompt appears allowing you to pierce the barrels and kick them. They then explode keeping the enemy at bay. You need to do this with the 3 barrels before you will be able to move on.