I don't know about all that. I use my right hand for most things, but on occasion - when balancing a ton of things, say, or when I busted up my wrist - I have to use my left. I still say I'm "right-handed" rather than "ambidextrous".
My best friend in college told me that the idea of having sex with guys wasn't a turn-off for him, but that it was girls who really got him horny. He said "I'm guessing I'm somewhere around 95 or 97% straight. I'm not ashamed of the gay part, but I don't think it'll ever be strong enough to bother acting on." Given that, I'd say it's silly to call him "bisexual but leaning towards straight". "Straight" pretty much covers it. He doesn't deny that part of him. It's just not a very large or important part, and of the commonly used terms, "straight" seems to apply (both to his inner sexuality and to his dating habits) a lot better than "bisexual". Might some guy come along that gets him to "try the other side"? I guess anything's possible, but I'd say it's unbelievably doubtful. I'd sooner bet on a Smiths reunion concert.
The OP has shown that he's been dealing with his sexual urges solely via pornography. And like most people who do so for long periods of time, he finds that after a while, the buzz starts wearing off, and he needs to "up the naughty factor" somewhat to keep the excitement going. And so he's going further afield - into bondage, into group scenes, into staged non-consensual things, into homosexual porn. To me, that just indicates that he's reached a point that he needs something more extreme (and "out there") to get off. And the fact that homosexual porn is lumped into these other "out there" fields means that he's getting off more on the "stuff I'd never do" factor of it, rather than the hot guys themselves. If it was EXCLUSIVELY gay porn that he was enjoying, then yeah, that'd be a big indication that he was gay. But most guys don't like all types of porn equally. They have preferences and favorites. The fact that he seems to be getting off on all porn right now - especially "different-from-standard-straight-porn" - makes me think he's just getting off on something different. If getting off to gay porn means he's at least bisexual, then we also have to assume he's actually going to be into bondage, role-playing, fursuits, and whatever else. I think it's much more likely he's simply compensating for over-exposure. And I think the true test will be when he shuts the DVD player and computer off, and starts actually dating. At that point, if guys are still turning his crank, then cool - he's gay or bi.
Lex