Yeah, couldn´t remember at the time of writing, if Lightfunctions actually suport color or are just black and white. Had the same idea of 3 lights later, and as it turns out, you don´t need to modify anything, just smack your video into a simple material for the light functions and mask each color channel properly, and throw it into 3 lights, one for each color of the video ^.^
A fast test with 3 point lights:
