So you are looking for a BALUN - (caps ok in this case!) BALanced to UNbalanced transformer. Seems like I found a similiar item from pimfg.com a year or so ago. Look at their Part #: NVA-P-860-BS78. Video Balun, BNC Female & RJ45, (Video On Pins 7,8) - PI Manufacturing Corp.
The package is way different then the photo of the PCB mounted one you've provided above, but you could unpack the version pi sells and solder it onto you circuit board I suppose.
Hope that helps some.