Select one or more files and click the View button on the toolbar or choose View > View Selected Files or press ⌘↩ on your keyboard or double click a file. BetterZip will open the selected files with the default application.
If you make changes to a viewed file in the external editor and save the file, BetterZip will detect the changes and give you the option to update the archive. You must not move or rename the file or BetterZip will not be able to detect the changes. You can also choose to ignore the change once or all changes to this file.