i get called into help with a computer problem, then the guy starts telling me how to fix it, lol, WTF
Funny anecdote. I think I get the reasons you're upset.
Outside of that small group of virtual saints, most normal people are far more narcissistic than they give themselves credit for, and some will attempt to get what they want as often as possible. From what it sounds, he places himself higher on his priority list than he does your well-being. Your colleague is riding the reputation wave, and is hoping you won't call him out on it.
If you're looking for an advice: People who explode come across as petty. It's not surprising, really. Anger and outbursts are generally frowned upon, so it'd be easy to assume you're in the wrong if you showed your frustration openly. The ones that keep calm and focused tend to prevail. So, I'd advise you to not lose your cool or call him out in a public outburst.
I'd also recommend you to put yourself higher on your own priority list, if you haven't already. There are some who are completely upfront about their own ideas and will ruthlessly set the record straight. They rarely get run over. If "your ideas become their ideas", then I'd suggest calling those ideas yours, even post-presentation. I've seen that happen countless of times. An idea is being floated around by a third person, until another gentleman nonchalantly claims ownership. Almost every time, the third person turns 180 degrees and credits this new gentleman. Even if he doesn't, the bystanders get it.
Also -- there's some subjective bias here but let me go on anyway -- adults play real-life Monopoly. We are all playing a very elaborate game of make-believe for adults. This is how it seems to be everywhere. In the boot camp. In the Congress. In corporate America. We are all playing these roles, although we do not have to. It is our fear, among other, less potent motivations, that keeps us locked into the mass absurdity. We believe in rules that have no basis in any other space outside of the human brain. It’s like the rules of Monopoly, the board game. For me, it's a joke, but for most people, the game is real. If you're willing to believe that, then, depending on your worldview, it can be a goldmine (or a source of depression).
You can try to observe the selected few who change those unwritten rules. From what I see, they do so by promoting their views. You can try to promote an altruistic atmosphere. You can choose to be strict about giving credit only to those who deserve it. Be open about your views -- that credits should be earned. Go on personal rants about it until it becomes the de facto unquestioned standard. Now, I realize this borders on the manipulative, so take it with a pinch of salt. Do what you think is right.
My last advice is to disconnect yourself from your colleague. I can't imagine being around him will be productive for you. I've seen people working together, splitting credits 70-30, until the other person (oft 30), ad hoc, manages everything. It's not magic or a sudden boost in performance, he decided to cut his colleague off. The other person never worked, he just showed up to eat his part of the cake, and then some more.
Having said this, it's all up to you. I don't know what kind of environment you work in. Our subjective experiences are likely to be vastly different, so what works for me, might not work for you at all! This is my experience of the society around me, so don't it too dogmatically.
Also, let me say something else. I believe that most people are not being consciously disingenuous, and likely this applies to your colleague, too. It's quite likely he's just doing too much navel-gazing. Most people do too much navel-gazing, if you ask me.