THEORY ONE:
THE HOUSE OF CARDS REPRESENT THEM. WHEN TAEHYUNG KNOCKED over the cards, I think it shows how his death caused everyone else's death, even though Jin tried to keep the House of Cards up.
That's why when Yoongi smashed the mirror (which gives you SEVEN years of bad luck; seven members?), the next scene is of the House of Cards falling down, and you can see Jin looking defeated, because there was nothing he could do to save them after that.
I think Taehyung getting out of the water represents him crossing over to the other side. I don't think Jin's dead because Jimin burning the picture represents those in the picture dying, that's why Jin isn't in the picture because he lived.
He makes those faces because he couldn't do anything to save the others. Once the House of Cards fell down, that symbolized the boys "falling down", and Jin wasn't able to save them. Hoseok woke up in the hospital after overdosing, because he went to the afterlife.
Jimin was already waiting for him there. Jungkook was winking at Jin at the end of the video, because Jin was the one driving the car. The boys in front of the car died, and Jungkook was saying hi to an alive Jin. Jimin burning the picture symbolizes how the six in the photo died.
That's why Jin isn't in the picture. He's the only one alive. Taehyung popping out of the water at the end symbolizes how he's crossed over to the afterlife. For those who think Jin died: If Jin died, then why was he the only one wearing shoes while the rest were barefoot in the group teaser photo where they were running?
Plus, in a concert VCR, they showed a video of an old man putting up a picture of BTS on a wall. As the man walks away from the photo, all of them disappear except for Jin. I don't think that Jin died.
credits to Yasmine E. Pang on YouTube