I see exactly what you see, but I do not interpret the darker area on the tape as evidence of a hole beneath it. They would not put a port so far forward, and everything had been accounted for already. I definitely think it is nothing more than a piece of tape.
I think someone already pointed this out but on the underside photo there is clearly some sort of hole in the same place as the tape that appears to be covering a hole.
It's a weird place to put a port. Perhaps they had an empty space there so they added a SD card slot? It doesn't look quite wide enough for SD but maybe it's Sony Memory Stick? (why?!!?) It looks about the same size as eSATA, but again, it's a silly place for that.
Couldn't HDMI be routed through the micro-DVI port?