It was in fact
@t-tony who came up with the cure for that.
We did a compression test on a warm engine where the results were very good and the compression was consistent through the 4 cylinders.
Then Tony asked me to test on a cold engine, when I did the test on a cold engine the numbers were all over the place.
I cured it over the course of 2-3 oil changes, in my case I used Mobil 0w-40 oil and used oil flush before changing the oil. We think it was sticky valves. I still get the very occasional cold start misfire, but you can't compare it to the video as it only ever happens once every few months and is there for less than 20 seconds.
@littlefeller has an M44 which suffers from the same issue I believe.