Did the video say the blue,red and green traces are from the same cylinder? My thought is: the spark plug had been taken off and insteaded with WPS500X sensor, so where the green secondary ignition come from ?
Not a silly question at all, the secondary ignition would be taken from the HT lead or you will have to use the pico extension leads if it's COP. All I do is clamp the plug to an engine bracket or somewhere safe (with the HT lead of course), and you will get the secondary ignition for that cylinder.