The JW tunes out, their brain becomes zombified and the complete lack of interest they have in debating is obvious.
There is something really un-satisfying watching them feebly defend their views.
To be fair, that never used to be the way with most JWs, as many on here can attest. The average JW used to be trained and encouraged to really defend their beliefs. Of course many used to do it in strange ways, but at least they would attempt it, not just fold up and run away or say something like "just look on our website"!
On the other hand, I'm not a fan of the opposite either - the kind of aggressive "street preaching" type of characters who get in your face with their beliefs. There rarely feels like anything Christian about them, they often just seem out to win arguments and score points, especially ones with a Trinitarian background.
JWs are supposed to be "ready to make a defence", not go on the attack. However, it's hard to defend if you've not been properly trained and practicing in the first place, as is often the case with JWs today.
It's rather like the concept of martial arts: on the one hand, real martial artists say you should only use the power for defensive means, not aggression, but of course some do use it that way. But in order to be ready to defend yourself, you still need to train and practice regularly.
Most of today's crop of JWs have little "training" and certainly do not really practice defending their beliefs (although to be fair, they are encouraged to do so in the meetings), so it's no surprise they are ill-prepared for many "preachers" that might approach them (whether street pastors, born agains and Seventh Day Adventists, or even other faiths like Muslims)
The pastor’s got charisma, but his argument’s a house of cards.
In this video, although he isn't aggressive in his approach, the "pastor" doesn't bring anything new. Those of us who were JWs "trained" years ago have heard all the standard trinitarian texts and concepts he claims here, and as stated by raymond frantz, it's not correct or persuasive at all to anyone who really knows their stuff.
And as ever, one has to ask: What is actually his motive for approaching these JWs, and how should they respond in the light of that? If his motive is one of questioning because he wants to know an answer (either for himself, or just because he's curious what JWs believe), then fine - a discussion can proceed. But if he is convinced of what he already believes and is simply trying to change the mind of the Witnesses, what's the point? Jesus did not continue trying to change or persuade the minds of those who were firmly decided in what they believed - whether the Pharisees, Sadducees, and so on, or even those in the crowds who did not really want to follow him. So from either perspective (his or the JWs) once it's clear the other "side" is firmly decided in their viewpoint, there is no reason to carry on.
I've terminated many such conversations after a few minutes and exchanges of Bible verses, when it becomes clear that is why the person is there - usually they will also admit they are a priest/pastor, they are trying to "save" me, or whatever. They often also start increasing the tension, such as was highlighted here by talking about "heresy" or they may begin to use name-calling or insults. Again, those are further signals that the person does not intend to be reasonable.
If neither side is going to change, then there is no point continuing. It's also why I largely avoid the interminable debates over the trinity on these pages too.
Just as any person approached by a JW has a right to say "no thank you" if they are convinced that Witnesses are wrong, so too a JW can refuse to continue a conversation if a person who has approached them is just there to argue.