This "bag", or whatever it is, is very interesting and i have absolutlely no idea what it is. I consulted several friends, including few SF guys, and neither one of them knows.
The photo was taken several years ago in hebron - it shows a snatch operation at the city market. There's actualy a vide clip of the entire op: http://www.isayeret.com/units/civi/y...amas-vid-2.mov.
The guy with back to the camera, as well as the uniformed man, belong to the israely police's territorial SF unit "YAMAS" (these are the guys that dress up as civilian palestinians). Note the colt commando with trijicon ACOG sight.