In the case of Darfur I think UN actions and political interventions, not just form the west, are crucial but you are right the film mentioned in Devilstower's piece sounds like a powerful tale, as described in it's press release, of "the agonized human face of globalization. While the flesh of millions of Nile perch is stripped, cleaned and flash-frozen for export to wealthy countries, millions of people in the Tanzanian interior live on the brink of famine". Here is the direct link to the film about Tanzania's fish and arms trade and an interview with the film maker.