Another Video Transparency Question

Hello hello,
I am working on a project in which I try to map different video layers on the different physical layers of an object.

The object is like sculpture that consists of different geometric shapes onto each other.
I read most of the video transperency threads in the forum but could not find the best way to go on.

In the attachment I’ve added my basic patch which is done for two video layers. Each video plays in a shape mask and I could not get rid of the black background of the renderer.
It would be great if you can guide me to find the optimal way to achieve this.
Thanks a lot,

vvvv_layered-masked-videos.rar (26.0 kB)

What would you like to see in place of the black background of the renderer?

I decreased the transparency of second layer in order to make you understand that there is another video in the background.
Normally the second video layer’s alpha value should also be %100. In that case, the layers underneath are not visible. So that means: the layered videos with masks need to be cut-out or they need to have a transparent background. As far as I got it is not possible to have transparent renderer background. How can I build another logic to achieve layered-masked videos onto each other?

With the help of Bluebox keying shader… I created a mask and applied it onto the video texture… It sound very simple right now… who believes that it took hours to find the right solution :)
Thanks for your interest anyhow!