It looks like it is setup to be (or become) a charge for service kind of thing. You have to make a new account. It has no connection with NI at all (other than name/content). All the courses say they are only available till the end of October.
I watched the entire Kontakt 101: Creating Custom Instruments. It's very short, 45mins total. Very, very short. Completely devoid of any real content, more like a brief video demo of some small, tiny portion of how to create a Kontakt instrument.
I have multi-year subs at Groove3 and MacVideoPro and have taken audio classes at a handful of other sites(Creative Live/ADSR/etc), compared to all these, I'm not sure this was a serious attempt or not. It was professionally produced but was really devoid of any real content. Maybe the Reaktor course is better, but I think you'd get more out of YouTube on how to build a Kontakt instrument.