This is to show how to hide the Video Pagelet that contains an MP3. (I have turned off the loop option to be less irritating with the short sound sample.)

How to do it:

1. Add a Video pagelet
2. Select the pagelet
3. Open the Inspector
4. Choose... the MP3 (I used a URL to the MP3)
5. Set the Inspector as follows and delete all text from the pagelet:

I have Editing Markers showing hence the 'green buttons' where text can be entered. The screen capture (above right) is of the pagelet as seen in Sandvox. The black text which can be seen is the default placeholder text and is not editable nor published.