Update 1:51 p.m.: Reuters reports that the Marines now say they've identified all four men in the video, and they've appointed a lead investigating officer to decide whether and what charges to bring against them, though none of them have been detained yet.  

This is not going to make Leon Panetta very happy. Two men in that widely-condemned "urination" video have been identified and investigated, offering more proof that the video is very real. A fake was what the U.S. and its Department of Defense were hoping for when the very ugly video surfaced two days ago, and even yesterday it seemed the Pentagon was still very evasive about the video's legitimacy, as an official told Reuters in a very roundabout way, "We don't have any indication that it's not authentic." But today an anonymous Marine Corps official gave CNN details about the investigation and confirmed that two of the Marines in the clip have already been identified and interviewed, but were not detained. The official added that the names of the men would not be made public. Due to sensitivity of the case and the international outcry not revealing names at this point does make sense and for news organizations it seems that cryptic information about unnamed people from unnamed sources is probably the way of the land. CNN also adds this tidbit of information, naming (with the help of an unnamed source) a very specific Marine unit and connecting that unit with a very specific region in Afghanistan(where the video was allegedly shot): 

While the identities of the people on the video haven't been released, the leadership of the 3rd Battalion 2nd Marine Regiment "is confident those are their Marines" on the video, according to a U.S. Marine official with direct knowledge of the initial investigation.

The unit, which is based at Camp Lejeune, North Carolina, deployed last February or March and returned in September or October. While in Afghanistan, the unit was based primarily in Helmand province.