Demo Builder is a flash creator. To export to flash your project, click to the preview frame or movie and click to the preview in internet explorer. Dont close i. explorer
When flash open in browser go to the demo builder path and the temp folder
example: c:\program files\demo builder\temp
In this directory you can find your project and the flash.
When you are close browser demo builder is delete your flash in temp folder, because you must copy your flash to another folder.