I am trying to recreate a live version of the picture below. I made that picture by blending a few layers using a darken blend. For the live version, I want live feed with the stage being a tv. 

The idea is a dancer is in front of the camera standing still and then their small movements create the same effect which accumulates. Though at a certain point I'd want older layers to dissolve away completely. I know there are blend modes in the effect mixer actor but I don't know how to go about setting the rest up. Any help would be greatly appreciated!!