My post on the same subject from 6 months ago:
Firstly, allow the user to select colors directly from the video with the controller, instead of having to move sliders to try and specify them indirectly.
Secondly, I suspect most users just want to have background passthrough while leaving the foreground unaffected. To achieve this, ideally you would have a set of passthrough colors with a wide range for the background and a second set of colors, with a smaller range and higher priority to protect foreground colors which are mistakenly removed (e.g. clothing).
Currently, if I remember right, Deo only allows a single set of either + or - colors, so I guess my request is that the + or - is specifiable for each color (or at least, that there's a set for each), and that - colors have priority.