This talk is about (the java understanding of) interfaces. The argument is that if you work with many many people on large scale projects, you basically need interfaces. I tend to agree, but I think large teams are a bad idea :)
So, the speaker also mentions that the other solutions out there (zope interfaces, py-protocols etc) are overly complex. Yes I agree, let's see...
Ah-ha, he uses decorators and inheritance to implement the functionality of an interface. And that seems to be it, mostly.
Well, I sort of like that the author tries to out of his way to make usage of it easy. The thing is contained in a single file. Speed seems to have been a focus, since it caches and optimizes for instanciation time.
Well, I don't know, it might be helping, it might be not, on any account there's no version up of it to date at http://www.mikeware.com/index.php