Another fine talk at Occupy Harvard, but I suggest that you listen to the previous post with Stephen Marglin's talk. Juliet Schor refers to it.
An interesting point that both of them make is that what becomes 'mainstream economics' is influenced by the broader political climate in the society more generally. It follows that actions to change that political climate feed back to help to change economics, creating openings in which critiques of what's currently mainstream economics can get traction.
At one point she says that there was a great disconnect between what macroeconomists were advocating (more growth to lower unemployment) and what climate scientists were saying -- more growth worsens climate change problems. The major exception among economists was Nicholas Stern, who argued that to undertake much-needed investments to tackle climate change would also help to address the unemployment problem.