The other talk Compiling and Optimizing Your Own Browser with WebKit (vimeo.com/18780399 for the video, http://slidesha.re/fPSvXX for the slide deck), mostly showing few tricks you can leverage to understand how your web applications work. For example, by using QtWebKit and capturing all the drawing commands and the corresponding timestamp, it is very easy to have a slow-motion rendering of your web page. As I showed it in the talk, it is even possible to go back in time, i.e. rendering your web page backwards.
Many other videos from SenchaCon 2010 have been published as well. Make sure you check them out.