I don't believe they said that in the video and in fact Google told Danny Sullivan this...

"Google says there’s a three year subscription required. Hardware will be upgraded at the end of the three years, if people want to continue on the plans.

If hardware breaks, it’ll get replaced under warranty. But if you decide you want a shiny new Chromebook with perhaps better screens, trackpads or whatever midway through the program, there seems to be no provision for that."

Source: http://searchengineland.com/google-chromebooks-out-june-15-3...