He says that they attached M16 mag pouches, four of them, to the sides. He wasn't sure what the two large pouches were made from. The M16 pouches look like this:
Unfortunately, Blackhawk no longer makes the Streamlined LBP (Load Bearing Pack), and so it is (like so much SG costume material) nearly impossible to find. Captain Cardboard says that a company called Eagle makes a copy, but that was years ago, and I've been unable to locate it. They may have discontinued it also.
You, like myself, are probably going to have to make do with the Blackhawk Day Pack from the previous post...if you can find one of those. I think that sticking the M16pouches on the other backpack should help improve the look.
UPDATE: I located a seller of these backpacks, or so it seems.
The company is selling them for around $80. My order was just over $90 with shipping. The description is as follows:
BlackHawk 60SLBP
This pack can be attached to your vest or H-gear with our quick disconnect kit (included) or act as a back pack with our Detachable Shoulder Straps (63SS00). The inside has a cinchable draw string liner and the outside has compression straps for complete gear storage. The cover flap has a pouch and 25 ft of 550 cord to act as a lanyard for your pack. The lid is secured by silent side release buckles. Made with our all new Nytaneon materials! CamelBak Compatible. The outside has slotted webbing for extra gear attachment using military Alice clips (HMAC04).
Dimensions: 15 1/2" x 13" x 3 1/2"
SLBP stands for Streamlined Load Bearing Pack, which I think, is what we've been looking for. Again, I'll let you know if I get the pack or a backorder notice.