The first 5 min was enough or me.
What the gentleman ignores is that it could be the electronics in his m/c that is causing the retard.
The only true way to see if the ign is retarding [ or advancing ] is to watch the ign trace on a dual trace osciloscope, where you can see the initial generation of the spark v the spark being delivered on the time axis. Once you have the time difference & rpm, you can calculate any retard.