I'll come back to that video, thanks, Stu, but my understanding was basically the same as this: "A countertenor is a male singing voice whose vocal range is equivalent to that of a contralto, mezzo-soprano, or (less frequently) a soprano, usually through use of falsetto, or far more rarely the normal or modal voice" (http://en.wikipedia.org/wiki/Countertenor).

In Section 2, by tightening muscles in my throat, I'm singing in falsetto to produce a contralto.