It sounds like you are creating an overlay .avi (32-bit). If that is the case, you can either create it as 24-bit or use alpha channel when importing the 32-bit avi into your projects.
Creating the .avi as an overlay (32-bit) should be ok, it will just look strange. When you actually use the .avi as an overlay in whatever video editor you are using the glow should appear normally.
If you create the .avi using 24-bit, you cannot use it as an overlay.