How to automatically insert code for an Xcode video demo

I've been watching some of the WWDC 2009 videos which include some video demos in Xcode. The presenters are using some sort of macr开发者_开发问答o or script bound to a keyboard shortcut to automatically insert some pre-prepared code at the current caret location. Each time they press the key, the next prepared snippet is inserted.

Does anybody know how this is done?

I believe the presenters use DemoAssistant which is Apple sample code.

It's a service that copies lines from a code file a line at a time.