blue?

can't help but think the plain black on white is a little empty and stark

considering some amount of blue/another colour/image

would quite gigantically increase workload

some possibilities in order of effort

 minimum effort required. one layer behind all the frames. easy peas.

some effort required erasing shape of items in each frame onto a separate layer of blue for each frame. alternatively fill background of each layer. slightly less work but potential jagged edges and general unpleasantness 

maximum effort required. going into each frame and adding simple shading in blue tones and some erased embellishments. would take literally forever to do on all three. roughly 300 frames of shading. so probably not this one.