I consider myself a bisexual, for the not particularly controversial reasons that I masturbate to both manly men and feminine girls (and androgynous people). The debate is merely over who else is gay.
Homosexuality is when you are sexually attracted to men. If being aroused by seeing a man fuck a lady does not count, then where exactly do we draw the line? (In a sense, I think that using the guy in the porn as a proxy for yourself is merely being gay for yourself.)