My spark checker is not very sophisticated: it's what you see in the video. Simple gap-adjustment/screw type. The spark only jumps about 1/4" in the gap: that seems pretty wimpy to me.
If you can recommend a more sophisticated spark tester, that would be great. Otherwise, I'll go to O'Rielys Auto Parts and see what they have to help me more accurately quantify my spark's high-voltage.