"real" video calling sort of snuck in through the back doors once people got webcams and MSN / Skype, and became mainstream / common in the 2000's with always-on internet, remote work, etc. And at one point the smartphone and mobile internet got in people's hands and (video) calls became casual.
I think the other part there is that it's normal people using them. What I mean by that is that in these videos, it's all very formal corporate people. And then the first people that really get interested in this kind of technology or who have an interest in futuristic stuff are / were the "nerdy" types. (I am probably living in a bubble though). But it was the average joe that normalised this technology.
This was what engineers were barely capable of, with the technology that did exist, but even most executives who were the type of user it was envisioned for never knew anything about it, much less had anything like this much desktop technology ever.
Everybody else in the non-executive category, even more of a complete fantasy.
IOW the difference between what you see there vs now is minor, compared to the real "backward" state back then.
Even though things like transistor radios were already common, you have to realize that in a huge percentage of dwellings in the US, and way more in the rest of the world, there was still not yet a single transistorized product.
I was a young math & electronics geek and was aware of more stuff like this than average.
Along with all the much more mature people, like the extremely rare engineering students who might want to work for IBM or something, this was exactly the kind of thing that was inspiring the movie "2001: A Space Odyssey" which came out the next year.
Anyone who had any clue something like this was already possible, could basically agree how cool it would be and was really looking forward to the 21st century when it would be here.
If the world was not destroyed by nuclear war before the 21st century got here :\