What the **** is this on the last picture ?

https://www.legitreviews.com/winfast...d-review_328/2

4's thing from the left, it's some kind of square port ?! black ?!

It's supposed to be some kind of optical connector but it looks totally different than:

https://en.wikipedia.org/wiki/S/PDIF

How the **** would one connect to this black square port ?!

Is it perhaps a place holder that needs to be pulled out ?!

Seems pretty stuck.

It's the square thing right next to that round port.

Bye,
Skybuck.