Do you recite it upon seeing a friend after 12 months when you see him on Zoom?

I think not. That is despite the fact that in my opinion one can join a prayer quorum on Zoom, etc. The reason is not that Zoom is not a meeting, but that in the Zoom era meetings and the breaks between them have no significance. It is only a matter of deciding whether to log into Zoom or not, and not a matter of flying to Australia, or traveling to Kiryat Shmona or to Eilat.

I didn’t understand the claim that it’s “a matter of decision”—after all, traveling to Australia is also a matter of decision. Maybe our teacher the Rabbi means that because there is an option to see each other, or at least get updated on the friend’s condition, at any moment, there is no reason to recite the blessing—indeed?

Traveling to Australia of course also involves a decision, but it is not only a matter of decision. You also have to travel, pay, and devote time to it, and not for nothing do very few people do it, and not often. But logging into Zoom is a decision that is carried out easily in a single moment. Therefore, a break in Zoom contact is not something significant, and there is no reason to recite a blessing over it.

It seems to follow from the Rabbi’s words that if they live really close by but do not see each other for 12 months, the same law would apply—that one does not recite the blessing? And in general, how do you determine when something is merely a matter of decision and when it is beyond that?

Jewish law does not deal with pathological and unusual situations. It speaks about the normal and general case. Zoom, by its very nature, is not suited to such a blessing. Without Zoom, even if someone lives next to me there is room to recite it (though not certainly), because we do not differentiate.