Defining Web 2.0

In the past couple of years I've read, heard and saw countless attempts to define Web 2.0. Not that it is possible, and the more realistic ones simply state that. But this video... without trying to define Web 2.0 but to tell you what's important in the social web, it captures your attention ending with the key points on why is Web 2.0 what it is... And what takes to be a part of it.