Semi transparent on screen buttons in Moto X?

Hi android army! I'm not sure if anyone else has noticed this, but in the leaked Rogers promo video I noticed that the on screen buttons for the Moto X were semi transparent in some apps. In the close-ups they were the normal black we are used to, but in some apps such as the camera, the buttons were almost transparent and you could see what was going on behind it. I'm curious to find out whether this is a Motorola thing, or a feature in 4.3.

Here's some screenshots I took:

Capture02_zpsbfe46ebf_medium Capture01_zpsaf0194c9_medium