What this filter is doing is telling GA to extract the part of the URL that's before the last / and use it to overwrite the URL value. You might want to test this filter on a testing profile first before applying it to your main profile.
But you also might want to check the configuration of your webserver and make sure each page can be accessed only at a one URL. Ideally, you should define what should be the canonical URL for your page (eg: /bucket-play) and make sure your server automatically redirects via a 301 redirect to /bucket-play when a user types /bucket-play/
Hope that helps.
Lothaire from the Google Analytics Academy Staff