No, that is correctly labelled as the platform controller hub. Before Haswell it was a separate chip package but is now situated on the same package as the CPU/GPU. The 2013 MacBook Air has Intel HD 5000 graphics, not Iris (5100) or Iris Pro (5200).

It could be related to the iGPU, but definitely not as traditional GPU memory. From Anandtech :-

"To allow the entire platform to go to sleep while the display is still active, Intel recommends Panel Self Refresh (PSR) to be implemented in Haswell Ultrabooks. The idea behind PSR is to put DRAM on the panel itself to store the frame buffer. In the event of a static display (e.g. staring at a Word document, looking at your desktop), the GPU frame buffer is copied to the panel’s DRAM, and the GPU itself is shut off instead of having to drive meaningless content updates to the display 60 times per second. With PSR, the SoC can go into its deepest sleep state (C10)."

Could this power-saving frame buffer be placed on the MBA motherboard instead of the LCD panel itself, contributing to the 2013 MBA's extended battery life?

Apparently this isn't the case, so what's the mystery RAM used for then? Is it related to the BCM15700A2?

The picture of the motherboard @ 2:53 in the video is of the old 2012 MacBook Air motherboard. Doh!

Y is most certainly a vowel in the Welsh language. Ouya however is not a Welsh word.

I covered the "Sandy Bridge bug" issue in my comment on Step 12 of this guide yesterday. The PCH chip in the machine ifixit performed the teardown on is a B3 stepping chip without the 3Gbps SATA bug. For full technical details of the S-Spec codes for fixed B3 stepping chips see this Intel product change notification - http://ghz.gr/sites/default/files/pcn110...

The Intel H65 PCH hub appears to be a B3 stepping without the SATA bug (SLJ4P). Buggy B2 stepping chipsets were SLHxx.