10-06-2014, 12:26 PM
I don't have a direct solution as I have never used a 3DS with a capture card. However, I have streamed from OBs with a Hauppauge capture card, which is not recognized by OBS. I did that by screen capture. I ran the default Hauppage capture program and then used screen capture in OBS to capture the program itself. This might seem like a bizarre run-around, but it's a temporary fix and gave me better video quality. Since your 3DS comes with a default recorder (I assume), open that program and leave the program idle, so that it will still play the video feed from the 3DS, just not record it. Then, use the screen or window capture to record what is going on in that screen. It's better than nothing if you can't get the plugin to work.
If you don't know how to crop the video you want inside OBS, I'll help with that also.
If you don't know how to crop the video you want inside OBS, I'll help with that also.