Is it possible to "intercept" a 20-pin FFC?
You have several options:


There are FPC to 0.1" pitch connector adapters available from many different sources (SEEED, Adafruit, Digikey and many others).
Solder thin wires directly to the connector. With some practice, you might be able to solder a 28 AWG wire to these pads.
Probe at some other point in the circuit.