The video shows how two Apache helicopters murdered 11 Iraqi people including two Reuters journalists. Two young children involved in the rescue were also seriously wounded. This is one of the publications Julian Assange is being indicted for espionage. He faces 175 years in a US jail if extradited from the UK. WikiLeaks obtained the video as well as supporting documents from a number of military whistleblowers. WikiLeaks goes to great lengths to verify the authenticity of the information it receives. They analyzed the information about this incident from a variety of source material and spoke to witnesses and journalists directly involved in the incident.
WikiLeaks wants to ensure that all the leaked information it receives gets the attention it deserves. In this particular case, some of the people killed were journalists that were simply doing their jobs: putting their lives at risk in order to report on war. Iraq is a very dangerous place for journalists: from 2003- 2009, 139 journalists were killed while doing their work. (source)