Jimbo's favorite Juice Box Boy, Matthew Yglesias, asks a question.
An alternative investigation might focus not on who leaked classified video of a U.S. military operations, but on the question of why that sort of video should be classified. Certainly I can see why the Army might have preferred to keep it under wraps—in the eyes of many it reflected poorly on their conduct—but it hardly contained operational military secrets.
There's actually a very good reason that gun tape is classified by default, but there's no reason you would know it if you haven't been to war. The gun tape contains telemetry information from the helicopter that reports "operational military secrets," for example, details about the movement of troops and maneuver units (to whit, the helicopter!). That stuff is there as part of the feed, and needs to be stripped out using software, which then requires verification that all the operational information has been removed. This requires the attention of someone with release authority -- in Iraq, normally a Division-level staff officer (often the PAO, who is responding to media requests for the tape), but sometimes a Corps-level one.
So, gun tape can be released, but it requires a fair amount of work. This work falls upon soldiers who are working 15-18 hour days already. So, there is a good reason for gun tape to be classified as standard procedure (in fact it does contain operational data); and there is likewise a good reason why gun tape is only released occasionally (it is a pain to strip the operational data and get it cleared for release, and the people who would be tasked with that pain are already vastly over-tasked).
If you want the tape for a given incident, however, file a request and it might happen. You don't have to rely on lawbreakers... er, "whistle-blowers," as some of you have chosen to style this fellow who released a quarter million classified documents, not to Congress or even the New York Times, but to a band of international computer hackers.