You can define a substitution list and apply it automatically or at your own discretion, or make individual substitutions. You can use this as a filter, or just for fun :)
My blog without add-on:
I work in international project and we have different applications in different languages. And I need to provide a support in this applications. I use this add-on to translate some basic texts (like menu items) before resources are translated by developers or in applications where I can not change the language. It speeds up my support and ability to find the right component in application with unknown language. You can also possibly use it in demo's: with this add-on your application doesn't need to support different languages, you can add translations just for demonstration.
And the whole beauty of this add-on is flexibility - you can configure different patterns for different domains, disable\enable some patterns and even export\import settings (which makes very easy to share them with colleges).
So, if you have an international application - it's good to know about existence of this add-on. Maybe it can help to speed up some of your tasks.