Yo,
There are three different video boards for Indigo2 products that sound REALLY similar. I've gotten the "Junior" Breakout pinout from Ian in the past for the Video-4-IMPACT Indigo2 board (that has one indycam port on the PCB and one DB26 port that gives your two S-Video and three RCA Videos (in total), grouped in IN and OUT). Mine is the: Indigo2Video-for-IMPACT board: SGI PN 030-0662-004 or 030-0662-005
You can find the boards here:
http://www.sgidepot.co.uk/sgidepot/partsspares.html
You seem to be asking for the Indigo2Video which might have been for graphics series: XL/XZ/Elan/Extreme? See the confusion?
I'm unsure if they took the same pinout. Email Ian and ask him, if so he still has that info. He may provide it to you or he may ask you to purchase one of this homemade breakout cables for 75 UKP. But it would be easier to help if you can post the SGI part number as the naming scheme was terribly confusing.
Also, I've not done this "mod" yet. But I discovered a really cheap third party product that has the correct cabling and ports/connector, but requires resoldering for the pinout (which I've not yet done). They are sold on eBay all the time for no more than $20, They are called the "pinnacle bluebox". The RCA video port connectors are still made (I ordered some from DigiKey). The bluebox is insanely easy to open (all clips), if you don't care about port colors you can leave them, if you do, you can replace ports with yellows and remove non-functional ones for a more authentic look. It's just a single PCB card with tons of wires soldered at the bottom PCB edge to a long DB26 connector (the correct kind we need for Indigo2). So the ONLY issue is taking the time to probe each pin, know the pinout, and reconnect the correct s-video and rca ports on the bluebox PCB to the correct wiring for the Indigo2Video board. So rewiring of the bluebox internally has to happen, but it totally doable once you've gotten the pinout.
I have several of these boxes and it's a winter plan once I have SGI work time. But I don't mind telling what to buy, if you can get the pinout from Ian then you're good. This box gives you ALL the raw materials (in place) that you need to make a great breakout box, you just need to alter the pinout inside the bluebox to the correct pinout for your video IO card.