Apply custom window mask:
Makes certain parts of the video object transparent. You can use this option to make a custom shaped video object play in your application.
To specify the areas that you want to make transparent, you need to create a transparency mask file in your favorite drawing program.
A transparency mask file is just an image where a single color represents the parts that you want to make transparent. Picture this image as being invisibly "placed over" your video object, like a mask or a stencil.
In AutoPlay, the transparent parts of the mask should all be solid black. Wherever solid black appears in the mask image, the corresponding part of the video object will be made transparent. The transparency mask acts like a "cookie cutter," cutting holes in the video object so whatever is behind it in the project can show through.
Click the browse button to select an image file.