I do have an image sequence (or .mov file) that contains an alpha.
I would like to use that alpha as a mask inside my material.

Is there any simple video tutorial that shows step by step how you can use the alpha as a mask?

Alpha can be inside a .png, or .tif or even rendered out separate as a black white .jpg

What I don't know is how to setup a material like that?
Thank you for any little help!