I worry thatv your brother seems more convinced after the video t ghe an he was before.
He loves the idea of an end of the world apocalypse/end times/sci-fi kind of story. When he was living his own life, it was a mess, but he genuinely believed in Buddha, angels, the hindu gods, norse gods, aliens building the pyramids, UFO's etc etc etc
Tell him what he wants to hear and he's like putty. But then if you seriously debate with him his ideas fall away. Which i think will happen here.
Cigs or not, they have him in his head, if not his heart. He wants the jw fantasy even tho he knows he can't live it. Just remind him that if he backsides after committing to it, you will be there for him. Does he fully understand that they will reject him like they do you when that happens? [And it will happen]
If he does progress further i will keep reminding him that it only takes one slip up and the elders will be just dying to disfellowship him. And he knows what that means.
I'll keep yis all posted.