Directly from Wikileaks (direct link to video page).
Warning: as you can imagine, the video contains brutal violence with many people being killed at cold blood.
No words can comment it. I would just want to praise the work of Wikileaks, one of the very few remaining research journalism media and the courage of the anonymous source. Truth and freedom owe only to the brave like them.
The murder of two Reuters journalists and several civilians, plus to injured children, happened at New Baghdad, Baghdad, Iraq, in July 2007. The US authorities have refused to release the recordings and have always declared that it was an armed confrontation with insurgents.
Update: notice that if you try to watch this video directly at YouTube (right click on video and select "watch on YouTube", you are demanded to register with the pretext that the video is not suitable for minors. With the same pretext, it has been censored in many media, particularly in the USA.
According to Ciudad Futura, this practice is common at YouTube with videos that show the reality of demonized countries like Cuba or Venezuela. The actual reference however, which you can watch embedded at CubaInformación, in fact shows not just the reality of Cuba but specially, as counterpoint, the reality of a "democratic" country: Spain (and there's some real institutional violence, which may be why YouTube decides to hide it).