True that some of that stuff would be tough to pull off against a skilled boxer. But someone who practices it a ton, against boxers, might be able to. Or, someone with crazy natural attributes like Anderson/Mayweather/RJJ in his prime might be able to as well. I'm not saying that the average person should learn that parry/chop to the brachial plexus/carotid sinus as a defense against a good boxer's jab or straight right.
Now, the parry while closing distance to enter the clinch/arm triangle on the other hand is a pretty solid technique and is much more easily applied. That's the one we practice.
Of course, like all techniques you need to have the time/distance and opportunity to use it effectively. If the attacker is very close and swarming you with strikes from every conceivable angle, that would not be the technique to choose. Or, if instead of them trying to "box" you with jabs and straight rights from a distance they instead just open up and start throwing bombs, then again that would not be the correct technique to choose.
Well, like I said before you need enough time/distance to be able to pull off any type of "precision" defense like the ones seen in the video. So the situation would determine the appropriate defense. But I tend to agree with you that he's probably doing it more for his personal growth as a martial artist rather than because he's planning on doing it in the Octagon.