Hi,
I am trying to do the tutorial Export Transparent Video clips for Video Compositing Using DaVinci, I have my scene ready with static png and images with motion clip. However, when I try to render the scene there is no transparent video box for selection. If I click export it does export into the same folders but has a grey background. There is also no Audio selection function under Quality compressor as per the video.

I am using a Mac and have updated to the latest version. Where do I find this box?  is the quick capture selection the same? as I can export transparent pngs. 
Thanks