I downloaded the Flex Builder Beta 3 today and decided to import one of the samples. But I noticed that the fl.controls.* package is not part of the distribution. It appears that you need to also have a copy of Adobe Flash CS3 to get this package. I’ve created a screen-cast that shows you how to configure your Flex Builder project to include the Flash packages. For some reason the Accordion.swc class fails to be loaded. So you may have to include individual Flash classes to avoid seeing the Accordion error in Eclipse. (During the screen-cast, I forgot that the audio was also being recorded. I turned it off sometimes in the middle, you get to enjoy Peace Train for a few seconds).