Export Video from PowerPoint with Transparent Background

Howdy, folks

While we're waiting for motion path animations to be added to Storyline, I understand that exporting a WMV or MPEG file from PPT isthe only option short of authoring directly in Flash, etc.

The problem, however, is that it seems to only want to export with a white bg. Is there any way to key out the bg as a transparency?

I suspect not, but I'd positively love to be educated to the contrary!

Cheers,

Leslie