It gives an interesting insight into the need to be exceptional enough for a small group of people (~1000 people) to choose to share your idea with their friends. He also covers why the traditional feature-based product pitch isn’t the best way to build a movement… you need to meet the needs of a small group in such a great way that they will think it is remarkable enough for them to share.
Seth also talks about tribes in this TED video.
And of course… here’s the book: Tribes on Amazon.co.uk
I spotted the Le Web video in Jeff Bullas’ excellent blog post from May 2010 on the 22 Secrets of Power Bloggers.