Natural with a hint of digital. Using different audio frequencies to create natural feeling overlays...film burn, overexposed elements, streaks etc..

This can be driven by audio and we can let it affect specific areas i.e. using luminosity...

In the examples below, these are flat 2D overlays, but we could also run the video through various 3D processing channels to create overlays / FX in the 3D space. i.e. having the FX being released from the human input that creates the music...