Traditionally flash developers have been more focused on the browser to deliver their content. While delivering the content through the browser, developers generally embedded their assets within the root swf. Honestly, there is no other way except loading these images off their servers but this could have resulted in a lag whilst the content was running
With AIR however, developers need to make certain changes to their applications to make them more apt for deployment on mobile devices. With AIR, developers get access to the file system and the assets for their content can be accessed off the file system instead of being embedded within the root swf. Assets for the application should be packaged along with the application and then should be accessed on demand by simply loading them using a Loader.