What is that? No HD-SDI signal. Black magic camera motherboard
It might be a custom chip built by Gennum/Semtech. The numers on the chip seem to correspond to those of HD-SDI cable drivers they make (e.g. the GS1678), in particular 0002E3 should be batch number 0002 (this very low batch number and the absence of an identifiable part name make me think of a custom chip), E3 on their packages is meaning RoHS compatible, and 1352 should mean that it has been manufactured on week 52 (end of December) of 2013.
The chip looks very similar to their GS1678 HD-SDI cable driver it has the same QFN16 package, and the pins seem to be used for similar/identical purposes:
Image from datasheet
In particular, you can notice that pins 9 (VCC) and 6 (DISABLE*) are connected together, which perfectly makes sense, and RSET (pin 4) is connected as required to a resistor (possibly going to VCC through the via). The top four pins are not connected (except maybe pin 16? not sure from the image where the track nearby is going), the DDI pins (1/2) have two ceramic capacitors nearby as expected per datasheet, and the output signal (going to the BNC through the matching network) seems to come out from SDO (pin 12) as it should.
Well, that looks like an impedance matching circuit coming from the right of it, going to the BNC connector, so my guess is it's some kind of RF (or similar) transceiver chip maybe.
For HD-SDI? It's probably the cable driver and output filter. Hard to see the numbers in that pic.