Hmm, that is a nice looking lead. But I expect inside you will find some very thin wires and an overall foil screen.
If I was doing this and could find a spare cable (unlikely) I’d make an experiment by cutting it and adding a few standard pre-wired connectors such that I could feed a set of three/four thin wires through the existing flexy umbilical.
I did this for two extra wires to my radio-linked reversing camera. With care and patience there is room for a thin coax too.
However, bear in mind that often in the multicore ‘video’ cables for reversing and security cameras the video is on just another ordinary wire inside the overall screen and not a coax - hence why I said experiment.
Adding just one more unscreened wire for the video and sharing the 0V wire for both video screen and power 0V might be OK for just half a metre. But it all depends on how the camera is designed to be used and where the 0V and video screen are combined.
My effort is shown here with pictures.