For what it's worth, here's my 2¢. Even
IF the factory head unit now contains the satellite receiver built in, AFAIK you'll still need the other components to make it work properly. Additionally the yearly map updates are not free, and although they can be obtained on sale for $99, why pay for the added expense (not to mention the negative reviews the NAV system gets in the forums)? Oh, and there's the sound quality issue as well.
I'd opt for a replacement unit from a company like Pioneer, JBL or Kenwood. Sure you could go with a Chinese unit, but what you save in price, you'll sacrifice in sound quality and functionality (slow boot times, etc.). On a related note, the manufacturer of the unit in the youtube clip also makes a unit that's compatible with the around view camera system.
If you still want to look into getting the OEM NAV unit, it's available on
eBay, but I'd check with the service department at your local Nissan dealership to find out exactly what you'll need to make it work.