ArcGIS Viewer for Flex: Creating a Custom Widget

I tried to dive right in to making my own widget for ArcGIS Viewer for Flex, but I couldn't understand all the working parts of a larger pre-built widget--So I started with a basic tutorial.
http://resources.arcgis.com/gallery/video/arcgis-api-for-flex/details?entryID=870F152C-1422-2418-A010-7C82711FE22F