This was absolutely machinable with late 1970s CNC mill. Probably pain in the ass to design with then existing CAD/CAM but ultimately this demo runs on same G-Code that was there in 1970s.
And as far as parlor ticks go this is not particularly impressive, compared to old ones like turning cube inside a cube on a lathe.
That’s a bit like saying “most large modern systems are written in C which was invented in 1972, therefore software engineering has not changed since the 70s/80s”. That machine is also probably not running a gcode flavour that would have made sense in the 70s anyways, with additions for active sensing, macros, etc.
Tools like UNISURF would probably not be able to handle the extreme level of detail on most of that model. The very long tool lengths you see in the video are much more complex than they look and require effort both from software and hardware to prevent chatter and breakage on titanium. The clearances in the video are also extremely tight in places, and while you could have guess-and-checked that in the 70s, it’s a very different workflow than the simulators that are basically standard use today.
CNC machining is a multi-billion dollar industry populated by smart people. While the fundamental technology of “spinning cutter driven by computer controlled motors” hasn’t changed in 50 years, the R&D departments aren’t asleep at the wheel.
Machining grade 5 titanium alloy (the most common one) is not especially challenging; it's easier than 316. Saying this as I did machine it personally on a manual lathe.
From the initial endmill size they use and the generous machine sizes (which can be extrapolated from chuck/table size) we can easily tell rigidity/chatter wasn't a particular challenge here. And the finishing passes are so delicate they don't even bother with coolant for that.
Yes the code to run all this would be a monumental undertaking in the 70s but it is done once and can be still entirely cost efficient as far as mass production is concerned. The thing new machines have is the running speed (for same precision work). These did improve a lot and make certain classes of products economically viable.
And as far as parlor ticks go this is not particularly impressive, compared to old ones like turning cube inside a cube on a lathe.