When it creates a SWF, Flix can embed variables with corresponding values that you provide. For instance, you can embed variables that provide the movie's author, title, description, and version or date of creation. This lets you create self-describing movies that carry their own metadata with them. This information can be used for indexing and searching. It can provide captions or data to populate a database describing the SWFs.
More imaginative uses are possible, too.
For instance, the SWF in Figure 9 links to my website. The URL-embedding feature caused me a problem on one occasion, when Flix created a SWF, which the Flix previewer was able to display, but which the Flash 5 player would not play. When I removed the embedded URL and re-encoded, the file played fine.