Cameron, who likened the plot of Avatar to the tribe's issue with the dam construction, could learn a few things from other recent documentaries about Amazon peoples. There's Joe Berlinger's Crude, which also involves tribal life disturbed by modern industry, though it's more of a legal doc than an ethnographic work. And Jose Padilha's anthropology expose Secrets of the Tribe, which details what not to do when studying and documenting indigenous groups. Such as allowing them to be experimented on or turned into personal concubines. I'm sure Cameron has higher ethics than that, but there's always the argument that merely bringing cameras into these societies is bad for them.
Now what I'd really like to see Cameron do with his 3D cameras down in Brazil is document his truthful answer to Piranha 3D, which we know he despises. How will the fish -- including some varieties of piranha -- living in the Xingu River be affected by the dam? Answer: many will likely become extinct.