Slate does a nice little round-up of what the Geneva Conventions actually say about this filming-of-the-troops issue. Apparently, nothing specific, as the convention was approved before the age of portable video cameras and what-not. The Article in question protects POWs from intimidation, insults, and public curiosity. The Slate piece goes on to indict Donald Rumsfeld for his double standards and duplicity in this regard. (And is just me, or has catching Rumsfeld being deceitful and morally repugnant become like shooting fish in the barrel?) Here's what Slate says [emphasis is mine]:

Rumsfeld is a bit two-faced on the Geneva Conventions. One year ago, Byers criticized Rumsfeld in the pages of the Guardian for the U.S. treatment of the hundreds of Afghan prisoners currently held in Guantanamo Bay, Cuba. The Guantanamo prisoners have had their beards forcibly shaven off, a violation of their human dignity under the 1966 international covenant on civil and political rights. And, they have been photographed by the press in shackles and with hoods over their heads. Subsequently, the United States limited media access to prisoners citing the "insults and public curiosity" passage from the Geneva Conventions. But at the same time, Rumsfeld maintains the prisoners don't have any rights under the Geneva Conventions because they are "unlawful combatants."[!!]

Byers notes that the "unlawful combatants" category is one of Rumsfeld's invention and not found in any international treaty. Under Article 5 of the Third Geneva Convention, military tribunals—not Donald Rumsfeld—should determine which prisoners should be prosecuted as criminal suspects and which should be accorded prisoner of war status. "The record shows that those who negotiated the convention were intent on making it impossible for the determination to be made by any single person," Byers writes.