I actually had that thought today (had not read your post) that this shooter might have been a video game guy - would like to know if the police / parents find that to be true...and not saying video games cause mass shootings. Just saying you're right - a lot of kids/others learn a lot about shooting from these games.
But they don't learn how to actually load and unload a handgun that way. Wouldn't that take some practice to have done what he did as efficiently as apparently he did?
That still doesn't mean military training.....
Do we know now that the Cho guy was definitely the guy who shot the girl and RA in the dorm? I know they said the bullets matched up with the guns - at both scenes - but did anybody see the shooter at the dorm? Seemed like that wasn't the case by the report at the news conference yesterday. And again, I haven't seen all the news of today about this so don't know what's been said about the dorm shooting.
You can learn how to load/unload a magazine fed handgun with less than 30 seconds of instruction. Ditto for a revolver. As for "practice", the guy was shooting people at close range. That doesn't require any practice. There is no marksmanship involved. Point and shoot. If you can point a flashlight, you can shoot a target at close range without ever peering down the sights.
I'm betting the guy purchased a bunch of magazines for each pistol and filled all of them before he headed out the door. Swapping a magazine just requires pushing the release to drop the empty, inserting a full mag and releasing the slide.