Two-sided connectorless USB on a PCB
A better picture, black diodes on white board. 

Big Clive on youtube did a video on these very same boards about 2 years ago, including a schematic starting at 1m50s.

It is a simple diode OR circuit. The diode simply prevents the grounded VUSB pin from shorting out, via reverse protection. General idea:



Important Design Consideration: The Diodes will induce a Voltage Drop equal to their Forward Voltage. Typical Silicon Diodes have a 0.7V Vf, while a Schottky Diode or Germanium Diode will have a lower Vf of 0.2V~0.4V. Plan according to your needs.



As for the extra copper on the data lines, that looks it's just for style. Like flames on a hot rod. It makes it go faster. The same style is used on most of the black boards.