I slapped together a quick demo, Animate a photo with Blender:
Using hooks to move mesh and alpha erase to create the keyed art. Realtime animation of the image is cool too. Sadly I had to slow down and render in the compositor 
Essentially you have re-created the After Effects puppet tool in Blender, neat.
Yeah, mesh warp isn’t exciting but I liked the real time interaction. It’s a shame that the alpha is only 1 bit in the VSE I could have created the effect all in realtime right there! Why can’t we have full 8bit alpha from GLSL in preview window?