I've got 2 layers of video. From one layer, I'd like to use just the Red Channel. On the layer below, I'd like to use just the G-B channels. The result being a composite of both layers.
I thought I'd be able to use the Arithmetic control to knock out the channels and use ADD as the operator for the top later but it doesn't seem to be doing anything - I still see the RGB image on the top layer despite the values changed by Arithmetic.