assign the sound's sync property to stream and replay/loop the timeline that contains the sound.
Just in case anyone else comes looking into this issue....
I quote the warning message after exporting a flash file:
Swiffy Flash Extension for Win v1.1.1 [Swiffy v5.2.0]
- Warnings -
Streaming audio is not supported.
The only solution I've found is to copy and paste the (event) sound keyframe as many times as needed along the timeline, and set repeat/loop to 1. On-the-beat replay not guaranteed.
The swiffy documentation:
...says sound is "partially supported", and then only by Chrome, Safari, IE9 and Opera (no sound at all in FF).
So far, testing, IE9 doesn't play loops, but maybe Chrome will (later, at home).
Chrome doesn't loop either