For OS-X systems past 10.8 an update of this application has been made, called BR-Renamer. While offering the same functionality it provides more features.
This utility allows you to change a lot of file names in one editing session. It displays the file names you select in an editor window. After you finish editing it applies all changes in one go. The original names remain visible while you edit the new names. Navigation between file names is done by using the arrow keys (or mouse clicks).