Thanks for the info!
I see that the the 1st gen. interface has a transparent case and the 2nd gen. (which probably comes with the JTV when bought new) is the black one.
I live in Switzerland and it seems that the 2 Gen. isn't available, new or used, nowhere in Europe...
Indeed the seller was using my ignorance - or is ignorant himself - and said, now that I've asked him, that he lost the interface and kit.
Before buying it, does anyone here have experience with connecting the 1st gen. interface to a JTV ?