Some of my stuff if a little bulky, I am using the Hammock Bliss bug net which refuses to pack down small and the Garcia adds a bit of bulk to my setup. However in the photo the other stuff sacks are kind of deceptive. They are silnylon dry sacks and I never can get all the air out. So when I strap them down the air moves to the ends of the stuff sack, kind of making a dumbbell shape. The top few rows of my pack are empty if it wasn't for the OES tarp stuff sack being short and wide, I need to get a set of tarp skins or a different shape stuff sack for it.
I think the video is for the MMP with an integrated hydration bladder sleeve. Effectively the MMP gets split into two halves with room for a bladder in the middle, right? This is the pack I sometimes want to try, it seems like it would be nice to get the water weight up closer to your back. MacEntyre also sells the "Water Bladder Carrier PEF insulated Water Bladder Carrier, holds up to 4L bladder $35.00" which I am not sure I have ever seen a photo of. My understanding is that this is a bag to hold the hydration bladder somewhat like Platypus one I bought.