You'll need to create a Pipe that will do that for you. Here's an example:
[[File:Rssdownloader_filter.png]]
Once you're done, save your Pipe, and run it. In the Run page, confirms the result, and click the RSS link to get the RSS URL for your Pipe. This is the URL you should use in RSS Downloader.
You'll need to create a Pipe that will copy the URL of the files into a new ''enclosure'' tag. The following example takes the URL from the ''link'' tag, and puts it in a new ''enclosure'' tag.
[[File:Rssdownloader_fix_enclosures.png]]
Once you're done, save your Pipe, and run it. In the Run page, confirms the result, and click the RSS link to get the RSS URL for your Pipe. This is the URL you should use in RSS Downloader.