A circuit inspired by the split module from the synkie modular video project which splits in two parts the video signal. One is the sync information, the other the video signal.

I want this circuit to be the input of a video-modifier box.

U2A is a buffer, R4 is important to terminate the video signal from the source(75R). U3 splits and recombine the signals. U2B is a video driver and boost the signal to 2vPP to give a legit 1V at the source. U4 extracts timing infomrmation from the video signal and drive the logic circuit which controls U3. U5A is an inverter of gain 1, RV1 brings the inverted signal into the 0-1V range.

The circuit may suffer from its crudeness and the absence of DC restoration.

As side note and maybe the most important, it may be able to make Vin Diesel's acting a bit more acceptable...