I would be more impressed with the philosophy in this presentation if I hadn't wasted so many hours of my life working around the 'final' and 'private' things the Java APIs try to prevent me from incrementally extending.
Java is a language built around safety, safety in the jvm, safety in the programs, safety in the APIs. Its a real pain to deal with these issues when you need to do something the library simply doesn't support. This is what we get for working in a language explicitly designed for "average programmers": safety, lots and lots of safety. And it makes sense, for larger companies with low quality and interchangeable programmers. But it still sucks to deal with.
I definitely prefer Python's "if you're an idiot you can go ahead and depend on private stuff, but we don't care if you get screwed" approach.
