That clearly looked and sounded as if the engine was just electrically shut off. And yes, kill switches do fail. Your plug looks great. If further testing happens to reveal a sketchy mag coil, don't buy one; I have a couple right here with me for you.

Plugs can go bad suddenly though, so you might try that too. I favor NGK over Champion. I used to be a Champion plug fanatic, but they are not as good as they used to be. And as the old saying goes; "Never be afraid nor unprepared to change the plug on a two stroke." I personally like changing them as a matter of standard practice after breaking in a new engine anyway. (Contamination due to rich mixtures, metal particulates, etc.)

AV8TOR