... and it was fun to see my charts in it! The lecture is reprinted here (pdf) or here (html). The charts I did are around pages 6-7 of the pdf, the ones showing the projected curve of global warming for various climate sensitivities, and backing into what that should imply for current warming. In short, even if you don't think warming in the surface temperature record is exaggerated, there still has not been anywhere near the amount of warming one would expect for the types of higher sensitivities in the IPCC and other climate models. Warming to date, even if not exaggerated and all attributed to man-made and not natural causes, is consistent with far less catastrophic, and more incremental, future warming numbers.
These charts come right out of the IPCC formula for the relationship between CO2 concentrations and warming, a formula first proposed by Michael Mann. I explained these charts in depth around the 10 minute mark of this video, and returned to them to make the point about past warming around the 62 minute mark. This is a shorter video, just three minutes, that covers the same ground. Watching it again, I am struck by how relevant it is as a critique five years later, and by how depressing it is that this critique still has not penetrated mainstream discussion of climate. In fact, I am going to embed it below:
The older slides Ridley uses, which are cleaner (I went back and forth on the best way to portray this stuff) can be found here.
By the way, Ridley wrote an awesome piece for Wired more generally about catastrophism which is very much worth a read.