The festival is using "Blackboard Collaborate" (previously called Elluminate Live!"). I have used this before and got it to work with as little as 28.8 kbps.
The "Hacking for Humanity" event at UNSW in 2011 used a similar time zone format. It started in Australia and then we handed off to other locations in turn, around the world for the next two days.
... In exploring the conference theme of futures for knowledge, keynote speakers and discipline practioners will be invited to share and examine the priorities for their subjects with colleagues from a learning and teaching background.
What will individual disciplines look like in 2025? What are the priorities that need to be taught to students in the years to come? What can we learn from current use of technology in teaching, and what lies over the horizon?
Over 48 hours and from three continents, keynote speakers from 12 disciplines will highlight what for them are the priorities in their subject areas before we move onto further elaboration in moderated discussions and technological showcases. ...
From: "Festival Format", Learning Futures Festival, University of Leicester, 2011