Yes, I have UseAlpha turned on for the texture. As you can see in the image, the alpha is detected by the Blender Interface.
I have tried turning on the mapped to alpha. It has three states, off, white and yellow. I have tried a render with each state.
With the map to alpha turned off, I get a grey background which is the default color of the plane.
If I turn it on (white or yellow), I get a black background which was the color of my comp background color in After Effects where I generated the Quicktime movie. This seems to be the flaw, the blender internal renderer has an error.
I have posted about this problem in the past, but no one seems to be able to re-create my problems. They generally toss my posts off as user error. However, I do believe there is an alpha problem in blender. I t also has problems with certain PNG files I have tried using as maps.
I have seen this problem go “unfixed” for 3 version now.
I like to do cutouts in my 3D renderings and I need the transparency of an alpha channel to accomplish my goals.