Some observations: And note I'm trying to be objective, not harsh, simply to get the point across quickly.
In the video, you prolonged the start up process by removing the choke. If it's cold, leave it on for start up. You don't have an accelerator pump to add extra fuel during cold start. But, the choke plates (not slides) closed at the carb entrance, increase the throat vacuum applied to all the jets. The throttle valve and main are mostly closed when the throttle is placed in the idle position. If you want more fuel during cold start, whack the throttle open while cranking with the choke closed, so the throttle valve can supply fuel as well.
D8 plugs don't run well cold, particularly at idle, as they are designed to wick away heat from the chamber. Don't expect it to start and run at idle when cold. Use the 2000 or 3000 RPM throttle position when it's cold for starting. Many other machines change the idle position upward when choke is applied. Honda felt that 750 owners were smart enough to operate the throttle manually when the engine was cold.
Those blacken plugs show conductive soot between the center electrode and the plug body. Soot is conductive. Why would electricity leap the difficult spark gap, when it could just meander the soot trail?
Plug chops need to be done when the engine is making power. Not much power is made by the engine when the bike is on the center stand and the rear wheel free wheeling.
Further, your complaint was idle, and you revved the engine so as to operate on a completely different jet supply than idle and the engine combustion was at far higher temps then at idle. Doesn't this seem a bit unreasonable to diagnose an idle mixture or start up issue?
Finding neutral with the clutch in will be easier if you make the rear wheel move (either direction).
Although, it is worth while to check the plug cap resistance, it doesn't sound (when running) like there is a specific ignition issue at all.
During electrical start up, the starting motor puts a big draw on the battery. While supplying these large currents, the battery voltage dips. As the coils rely on source voltage to make spark voltage, a dip in supply means a dip in capability. Cold engines are harder to turn over than hot ones, leading to higher current draw from the starter motor.
If the bike's electrical connectors, switches, etc. in the path between battery and coils is also losing voltage, the starter dip plus those losses might make the spark marginal during electric start. And, this would be worsened if the headlight is on as well, adding it's current draw. To determine if this is part of your start up issue. Use a voltmeter to check the voltage getting to the coils during start up. If below 9V, then suspect a spark problem at startup.
Finally, quick starts were alway indicative of recent tune up completion. Valve settings, timing, dwell, air filter, cam chain adjust, and new spark plug all made the bike (when new) start quickly. They still ran crappy when cold, and D8 plugs extended the "crappy" period duration. Extra RPM would compensate for this somewhat. But, if the engine is cold, don't try to start it with the controls set where it is known to run crappy.
Hope this helps,
