In the Youtube video, the "demonstrator" shows a couple of small objects that look like washers - not parts of a spark plug - which have no effect. He then bends down and picks up "something else" which he throws and shatters the window. The object he picks up is never shown, and I don't see any description of what actually was thrown. There also seems to be a "gap" in the video that isn't present in the audio, indicating the sound was dubbed over after the video was edited.