Outputting a video with alpha Fusion beta for mac

I'm playing with Fusion on my iMac and MacBookpro. First of all, can't get any prores flavor out of the saver. H264 and uncompressed 422 work, but other than exporting a sequence of pngs, is there anyway to save a video file with an alpha on the Mac right now?

Yes, on the saver there is a button 'attempt to save alpha' this will saver alpha if the codec supports it.

There are more options in the saver format tab, as well as the Quicktime settings which are in the preference file.