The photo got interpreted as the kid starving and the press played it up like it was Dachau. Then it was off to the races with the Brit and US press who could get a scoop on a concentration camp the evil Serbs were running, when the kid was outside of the fence in the open, and the photo was taken from the inside.
The name of the documentary is “A Single Frame”. He watched it on Amazon - here is a link to the picture.
It isn’t the same picture as the one you mentioned.
The photographer’s name was Alexandra Boulat. She passed away in 2008 I think from an aneurysm.