I do video effects work and I'd suggest this could be very useful even with jitter, if you allow expanding the selection. A lot of time is spent creating "garbage mattes" for green screen footage, basically just roughly rotoscoping out the background so you can do key removal on just the important bits. So you could even massively downsample the video for your processing and still have a good enough matte.
Although, with your tech, and the more limited problem space of green screens and poorly lit green screens, you could probably make a pretty amazing tool to do the entire green screen removal.
Although, with your tech, and the more limited problem space of green screens and poorly lit green screens, you could probably make a pretty amazing tool to do the entire green screen removal.