I’m trying to texture a plane with a movie texture with an alpha channel, but I cannot for the the life of me get it to work. I feel like I’ve tried just about everything. Am I missing something or does the fact that it’s a movie file not support an alpha channel.
For alpha channel you may need a separate “pass” of the movie as greyscale (black and white) alpha. Plug this extra pass as a texture into the alpha of the material. Most movie formats do not support inbuilt alpha, so the extra pass is needed.
True Apple Quicktime does support an alpha, but you have to choose the Animation Codec. I don’t think Blender supports this, however, it just runs everything through ffmpeg so low quality is all you can expect out of any movie file you make with Blender. If it even works at all.
Just use PNG sequences with an alpha and create you final movie in an external compositing program.
Or I guess making the movie a PNG sequence would be better anyway.