I don't think that's an argument against the point JP3 was making. In your example, the guy in the video might see an armbar used effectively on the street and could therefore reasonably draw the conclusion that armbars can sometimes be used effectively in a street confrontation. He cannot draw the reasonable conclusion that his own armbars are any good and would ever be effective (on the street or elsewhere). For that, he would need to personally go through the sort of pressure testing which would (in his case) expose just how bad his technique is.[
i think this logic is a little flawed. I'll try to explain. This guy has learned an armbar. I think it's terrible technique. But it kind of, sort of resembles an armbar.
If he sees someone on "the street" execute an armbar, according to the logic in this thread and your post, he could use that as validation that his training is sound. After all, he learned it. And it seems like he's teaching it.
I see a real problem there. Dont you?
JP3's comment that you quoted was not (assuming I am reading him correctly) saying that "I saw this technique used in a street confrontation which looks like one I do and therefore my Aikido is sound." He was saying, "I learned this technique in Aikido. I also learned it in Hapkido. Rather than worrying about which art 'owns' the technique, I'm just saying it's part of my personal toolbox." He's not claiming that his training is validated by the success of the guy on the street.
Perhaps it's more directly to your point that JP3 might be mistaken as to whether the guy on the street was really using the same technique as he uses - just as the guy in your video might think he's doing the armbar like a BJJ guy. I suppose it's possible, but considering his background (41 years training martial arts, with dan ranks in Tomiki Aikido, Hapkido, Judo, and TKD, plus an instructor certification in Muay Thai), I'm willing to bet he's got a pretty good eye for these things.