I pointed out that Phil's very first step took him off the line.
But it didn't...
Looks like we have to pull out the GIFs again.
The attack:
Steps straight in, inside the guy's stance to slap then grab his arm.
The initial attack is not within striking range.
No reason the guy could not counterpunch directly with the rear hand or see the obvious attack on his guard coming and recycle it into a punch before it can be grabbed.
Instead he tenses up and allows himself to be pulled while his rear hand falls asleep.
The response to the counter (of stepping away and turning for no reason without attacking):
Again, steps straight in, inside the guy's lead leg to slap then grab his arm because the initial punch is out of range.
His foot is clearly not stepping to the outside of the guy's lead leg, nor is he using any sort of body method to move off line of a counterpunch similar to anything shown in drop bear's clip against southpaws.
The guy takes a large lateral step for no other reason than that he was told to.
Phil doesn't start moving off line until the guy steps away and turns, without attacking.
This works because the opponent supplies him with a strong-arm
taan-sau to pull on, steps away, and doesn't counterattack.
The entire strategy relies on their being a stiff arm to leverage against the opponent, but it may not be there when you go for it.
Then you're unable to stop someone from turning by pressing on their arm that isn't there, but it wouldn't matter because you stepped straight in and attacked from out of range and could be directly counterpunched instead of scaring the guy off into a pointless sidestep.