i saw video , but there is no relation man, current comes from coil in magnet, which i guess is fine on ur bike , coz when it starts all ur electric connection works which shows current is coming from generator,
only culprit is ur battery side connections which are responsible to provide current whenever generator isnt working and also this problem has nothing to do with spark plug ,
regarding ur engine running fast adjust ur idle speed from the screw on carburetor or get it done if u dont know how, and make sure u have not accidentally pushed up the choke