If this option is enabled, the matching files or folders will also be backed up. Even more data!

If you have specific files not normally backed up, that you also want to back up, entering a regex here which identifies those files will include them. All files with a name matching this regular expression will be backed up. If the expression is invalid, it will be disregarded.
Note that this only allows filename patterns, (not full ant-style patterns) but positive and negative look-aheads are effective at filtering out the primary folder.
Example:
^(email\-templates|.*\.jelly)$ will include email-templates/*.jelly .
^(?!jobs)(?!plugins)(?!logs)(?!users)(log|.*\.xml)$ will include *.xml and log/*.xml while skipping the jobs, logs, users and plugins folders under the home folder.