Watching the video, nice landing btw, and reading the caption below it, the engine did sound rich. Unlike glow engines gas engine are not suppose to be tuned rich for breakin. That is accomplished by oil to gas ratios suggested by the manufacture.
A gas engine is to be tuned for max performance, i.e. set the hsn for max rpm then back off slightly, and lsn set for best throttle advance from idle.
A breakin period usually is a 24-32:1 oil mix  then switch to 40-50:1 oil mix after a specified amount of runs with the engine.</p>