He spends a half of the lecture by explaining the quantum and quantum gravity revolutions from the viewpoint of the decreasing number of observables we can consider and the increasing demands on the "infinite size" of our apparatuses that are requested to produce precise measurements.
He also argues that there can't be any "atoms of space" despite the multitude of research programs that have been failing for a few decades because they would be in conflict with the special relativity (and its Lorentz contraction), a favorite insight that your humble correspondent likes to spread because many people are ignorant about it.
The second part of the lecture is about the third, twistor-inspired description of the maximally supersymmetric gauge theory.
In his opinion, there is a whole new T-theory that forms a triangle with the AdS and with the CFT description of the same physical system.
An interesting technicality: if you can see a video above, it's because your browser supports HTML5 where videos may be embedded simply by the following command:
<video src="http://media.scgp.stonybrook.edu/video/20120411_2_Arkani-Hamed_qtp.mp4" width=407 height=300 controls>TRF found out that your browser does not support the HTML5 video tag.</video>This simple video tag is how video should be embedded in the modern era; the content in between the video and /video tag is interpreted by the browsers that don't support the tag. Too bad that not everyone supports this technique. It's plausible that Chrome is the only browser you sometimes use that will play the video above. Oops, it actually works in MSIE9, too. Firefox shows the video window but says that it is an unsupported MIME type.
If you don't see any video above, go to this page that plays the MP4 video via a Flash player (jwplayer).
If you need to musically explain quarks and hadrons, listen to the song above.
In this 3-week-old 4-minute Harvard video, Lisa Randall talks about teaching.