Funny enough, right before that at 7:18 is where he says, "tell me who had that...Not us and not the Russians, and nobody I know of." So you obviously heard it.
Human's don't have it, that's what he says. So regardless of whether he means aliens or not, he's saying it's not human technology. Bill Nye does not offer an explanation because there isn't one, which is correct. And if he would have, I am quite certain that most people like Jacobs would have decried, "DEBUNKER!!!!" because that's the game.
I'll stick to the "I don't know" because if I attempt to use a mundane explanation I'll be labeled an evil debunker
I heard that, I also hear you assuming that alien means non human.
I think that he was trying to say the same thing you are, he is basically just trying to say "I just don't know".
In my opinion that is the most reasonable position to take.
For you to say "I just don't know", then feel that Jacobs is being a jerk by getting bothered about being challenged on this exact same stance to the point where he feels that he has to defend the position by pointing out blatently that what he saw was not a craft that he knows of that the US or Russia could produce with the technology of the time is not him being a jerk. He was going to get Trolled into that conversation from square one by Bill Nye (4:33 - 4:36 he said "that doesn't mean they were A... That's quite a leap" he almost said alien) already had the intent to drag the conversation down the "alien" path.
Then he tries to come up with an explanation that (8:24) that the technology to reproduce images like this on film in that year did exist (sure they absolutely did). As if the military had hoaxed it during a missile launch training exercise. Try and explain that line of thought with logic without making some leaps of your own. It may be mundane but you will have to fabricate a hell of an explanation to put that on the table as a legitimate possibility.
I agree with you too though. I am much more comfortable saying "I just don't know" because I am a skeptic too, I have to be. But the fact that these things exist cannot be unlearned once you see one, so we just have to respect each others perspective. We all get defensive when our world views are challenged but that's part of learning. If you called me a liar for seeing a flying saucer I would think you were kind of a jerk too then my reaction would be to defend my position. but without your own proof you have nothing to go on, but we might get there one day people like me are trying our best to get people like you the proof you need. we arent satisfied with just telling storys. It is so frustrating to have had an experience but not have anyone to share it with, and in some ways I envy you for not having had that occasion.
Being skeptical is good and having an open mind is good, but we need to balance them. Too much of one or the other and things get silly.