I tried to use a url (like http://www.example.com/dbname.nsf/notesunid/$File/filename.mp3) to play a sound attachment from Notes document on Domino server 9.0.2. I hope it can play directly by streaming but it always download the file. Any suggestion?
You should be able to use HTML5 Audio for this. Here's a simple example:
<audio src="/dbname.nsf/notesunid/$File/filename.mp3" controls></audio>