Using Masks for compositing

Can anyone recommend any tutorials on using masks in Embergen? Particularly for output to sequences and compositing. For example, what does the mask shapes input to the Volume node do? I can’t seem to get it to display anything obvious or useful - and (being new to this concept), I don’t understand how other types of masks (RGB?) work at all… Any help would be greatly appreciated!

Check out this tutorial we just recently released: EmberGen Tutorial: Creating a Live Action Torch Shot with Animated Meshes and Camera Imports - YouTube