1) Add any emitter to an new project
2) Click “Save Output” button
3) Choose PNG or TGA output, supply filename
4) Check “Save Alpha” option
5) optional: uncheck “remove black bg from RGB channels”
You can also save as AVI if you use a format that supports alpha (like HuffYUV or Lagarith) and the codec is configured for an alpha channel.
If you’ve done this, what are you using to view the image or movie? It may be that your viewer or video editor is only showing the RGB channels.
Alan.
http://www.wondertouch.com