A stencil for an animated background is a nice element for motion graphics. Unfortunately, the compositor is not always well-suited here. But Cycles comes for the rescue!
When I created this background stencil some time ago I found the lack of direct interaction with images in the Blender compositor both slowed me down and was outright annoying. But I found a nice workaround by using Cycles. Watch this tutorial if you want to find out how Cycles can help you in motion graphics work, even in realtime.