To access these .mp3 files, you may need to download them. You can right click on them to save the file. Some default settings in the Firefox browser may not play the whole file, so you may need to download the file or change the application that plays mp3 by default. To do this, go to Tools > Options > Applications in Firefox. The .mp3 files should play automatically in your browser if using Internet Explorer, Safari, Opera, Google Chrome, etc.