I did some "research" tonight and watched the beginning of the video in some detail.
Here's some RPG launchers seized in Iraq:
The encyclopedia of mostly truths (Wikipedia) tells me:
A telephoto lens of the type they appear to be holding isn't that long however not the similarity of the flared end of the RPG vs the widening lens and lens hood of the camera. There are some similarities.
The other people seem to be carrying weapons. I've taken screen shots specifically of two of the guys who as you watch the video quite clearly have weapons. I'm not as high tech as wikileaks so I've just simply circled in red.
Same guy in both pics, two different angles. AK-47? In the second shot it looks longer and thinner than an AK and more the profile of a loaded RPG launcher. I note the comment at the time which says AK-47.
The guy standing beside person above. That is the profile of an AK-47 and could be what the soldiers are referring to.
Here is the first guy standing still. This is not the clearest capture but I note the weapon seems to go up to at least his waist and seems more long and thin than AK-47 like.
And finally here is the camera. Even stopping it and going back and forth a few times it comes and goes quick so the assumption of an RPG is plausible. I do wonder if the guy who says "RPG!" is looking at the camera view or something different.
I would say it's hard to tell from this exactly what was going on and I do find it interesting the video editors don't note the weapons. They are there so it would make sense that gets pointed out. I would also like to know if Reuters or many news agencies send their reporters out to tag along with insurgents. I recall seeing some Israel/Palestine war photos where the photographers were right there with the Palestinians.
In a quick search there are a bunch of photos tagged Iraqi Insurgents taken for western news agencies. For example here's one with an Associated Press watermark when viewed on the original site .
My point in all of this is not to say the photographers should have known better or not been there or that it's somehow their fault. My point is more, there are lots of things which transpired here and everything needs to be taken in a complete view...something which I don't think any of us can do from this footage.