Here's Kendall Taylor: 'When playing double-thirds legato it is not possible to join both notes of the thirds smoothly when connecting the finger groups, nor when playing the thumb on two consecutive notes. The illusion of legato must be created by securing the smoothest possible progression between the upper notes of the R.H. when rising and the lower notes ofthe L.H. when falling;...' Principles of Piano Technique ad Interpretation.
You state that as if it runs in contradiction to the consensus that everyone who posted in the thirds thread reached? Do you feel it contradicts what anyone said? If so, I suggest you reread the posts. Not a single person has disagreed with what is stated there and many already made the same point.
What everybody agreed was that legato in the upper voice
does not automatically guarantee a legato illusion (and particularly not in your film). The premise is correct- but the point is that it does not tell the whole story. Again, I'm inclined to wonder what he wrote in the (...). Regardless, legato is a sound that is either heard or not heard. It is not the result of satisfying a checklist and no number of sources or citations (quoted out of context) will change massively obvious gaps into inaudible gaps. Understanding the premise of joining one voice is the very beginning of mastering legato thirds- not the finished product.
You can repeat the premise for legato illusion as many times as you like. Nobody disagreed with it. However, if you think that amounts to 100% of what is required, you are mistaken. If a magician is seen pulling the card out of his sleeve, it's no use for him to cite Ali Bongo's instructions and say that he followed them correctly- just as it's no use to play extremely non-legato sounding thirds and cite a "correct" fingering or methodology.