Sorry for the length, but, I felt that this topic deserved a certain degree of detail.
Couple of things. First, I fundamentally agree that videogames doesn't desensitize people to violence the way that it's portrayed in the media and have no interest in censoring them for a variety of reasons. Also, I have little respect for the NRA's blatant attempt to shift the scapegoating from guns to games. It's not an intellectually honest position. However, I have some bones to pick with you, Jimothy.
It's a little difficult to parse what sections of your shows are hyperbole and what sections are "straight talk." So, regarding your offhanded comment, "every sane civilian is going to be terrified of guns," is at best ignorant, and, at worse, quite offensive. On the one hand, you may just be suffering from a false consensus. You have a fear of firearms. Your fear of firearms leads you to avoid them, so, you never get over your fear. Since you've always had this fear, you presume most other people do as well. This is a common logical fallacy and everyone falls prey to it at some time or another. Succinctly, just because you feel one way doesn't mean that everyone else does or should. You need a logical argument. The alternative is that you're honestly saying that the roughly 80 million legal gun owners in America [citation needed] are crazy and just didn't bother to give the argument behind it. As a gun owner, I'd like to tell you to bite me. People who have been taught how to use a firearm tend not to be afraid of them. Certainly, there's a healthy respect for them (there are no accidental firearm discharges, only negligent firearm discharges) but, that's not fear. And the notion that a qualification for sanity in your mind is sharing your phobias is offensive to me, and I presume quite a few others.
Now on to the part that's really going to upset some people.
Videogames do make it easier to kill people. Please read the entire argument. They do not make you more likely to kill someone, but, all the evidence I've ever seen shows that shooters are actually murder training simulations. Again, I don't believe in censoring videogames, in much the same way that I don't believe in banning guns, but, the evidence is pretty strong. I direct you to the book, On Killing, by Lt. Col Grossman (ret.), an Air Force psychiatrist who wrote the work on the psychological effects of killing another individual. I will summarize this theory.
Almost all humans naturally resist killing someone. Alot. As in, they physically won't and if they do, they suffer extreme psychological trauma. You can become acclimated to it, but, it's not easy. 2%-3% don't have this psychological aversion to killing others, and they're called sociopaths. Sociopaths are not intrinsically bad people, they just don't have the same innate hangups. Anyway, throughout history, research has shown that wars have been far less bloody than they should be. We have good data about the Civil War, how quickly regiments could fire, reload, and fire again, etc., and they found that the really bloody battles of that war should have been over in less than an hour, because, everyone would be dead. And, it's not accuracy either, mind you, the tactics had taken that factor into account. The implication is that most of the soldiers chose not to fire, or deliberately shot at a nonhuman target (the ground, the air, whatever). Indeed, many guns have been found on Civil War battlefields loaded several times, as if the soldiers loaded, pretended to fire, and reloaded. This is corroborated by research done after WW2 in which soldiers admitted to the same and has been reproduced since. BTW, much of the deaths of these bloodier wars come from artillery, bombings, etc., indirect killing systems that make it much easier to psychologically kill someone than to put the knife in yourself. Distance helps the psyche. Easier to shoot someone than it is to beat them to death with a baseball bat, and it's even easier to fire a cannon at a distant huddle of people looking things and even easier still to shoot at a set of coordinates that you can't see. Clearly some soldiers overcame their aversions and shot to kill (and some didn't have any) but, they were certainly in the minority. (There are also racial, authority, and group dynamic driven elements that help as well)
However, by the end of the Vietnam War, this was no longer the case. Lt Col Grossman states that up to 90% of US combatants in Vietnam fired their weapons at an enemy. Why the monumental shift? Because military training had changed between WW2 and Vietnam in subtle but powerful ways. Marksmanship training moved from shooting at bullseye targets to shooting at man shaped silhouettes that would pop up and then get knocked down. similarly, the Pavlovian rewards for success on the range of medals, etc, and the punishments associated with failing, were more clearly defined. The act of see man-target, acquire man-target, fire, receive reward, became ingrained by repetition so that when in the field, servicemen would do exactly that, without actually thinking about what he was doing until after. This relates to the stories you hear about police shooting incidents, usually with innocents as victims. The officers see a suspect reach for something that could be considered threatening, training kicks in, and a few seconds later, their magazine is empty, and they're staring at the body in front of them wondering what happened. Indeed, this same effect could very well be tied to why servicemen in Vietnam suffered much higher rates of psychological injury than previous generations. More of them actually tried to kill someone, and though they had been trained better, there wasn't a psychological support network for coming to terms with that. We're better about that now, but, still probably not enough.
I strongly suggest you buy the book if you want to know more.
So, videogames. Shooters share a lot of the qualities that made the post WW2 training so much more effective. You're rewarded with scores and achievements for quickly and accurately shooting many moving man shaped (usually) targets. Decades worth of research on killing people suggests that this helps individuals to overcome the psychological aversion to killing, at least enough to commit the act. Logically, videogames makes it easier to kill people. Make no mistake, they're no more likely to. In the same way that the aforementioned sociopaths are not intrinsically murderers. Most are good, decent, law abiding, God fearing people, like the rest of us, because, that's the people they were taught how to be. (Far less than 2% of the population are actually violent criminals) Most people who own, use, and train with guns do not go out and kill people with them. And so, videogames don't cause you to kill people, either. It doesn't desensitize you so that the thought of killing doesn't hurt you, deep in your soul, it just makes you more capable of it, should you so decide. Incidentally, in these mass shootings, the assailant seems to have run into difficulty/ been stopped, when their weapon jams. Military personnel are well trained in dealing with jams (tap, rack, bang), and to a lesser extent, gun enthusiasts, but, when was the last time you had to clear a misfeed in a shooter? This is my own theory, but, I suspect there's a correlation between those two items.
Succinctly, there's a lot of evidence out there, I recommend that you go look it up. I'd start with On Killing.