You can also make masks with shapes. I have mickey head shapes and castle shapes I've made for clipping masks. I watched the video and at the end she merges the layers, making it difficult to use as a mask (I couldn't find the next video). You want the "white" area to actually be transparent. The mask should be a solid color (the color doesn't matter for a clipping mask). If you use it as a layer mask ( I think you can only create a layer mask in Photoshop), then the color does matter, as it will be transparent.
Anyway, you can put a bunch of shapes together on a regular layer and clip it. I hope that all makes sense!
