Is this gay?

This clip immediately made me ask if it was gay to be aroused by it? I think it is because both humans have penises. It is ok, however, to watch and enjoy a she-male shag a woman; that's no different to watching regular man-on-bird porn. There just needs to be one penis-less person involved - and no two penis-equipped people can engage each other sexually; in the midst of a threesome, for example. Still, I must say, I find all of this very confusing.