I want to emphasize that these are just my thoughts on what the mv could mean.
GDRAGON. He’s draped in fancy clothes but that doesn’t take away the loneliness resonating from within. He has a tattoo saying “truth or dare” across his neck, to signify that simple things that he/people say(s) and do(es) (i.e. his actions and the rumors that surround them) can cost him his life. He has a noose tattooed by his ear. Considering that a noose was used for public execution at witch trials, it could mean that if gd committed suicide it would be due to the witch hunt-like rumors from the people who hate him. He lies limply on the floor or in the bathtub, both of which are in darkness. The phone is there for him to reach out, but he does not grab it. He instead uses the bat to destroy the lamp so that his surrounding becomes even darker and the mirror so that he doesn’t have to bear looking at himself (aligning with the lyrics). The sign says do not enter, but he ignores it. He lies feebly in the middle of an intersection as if he doesn’t care if he dies.
TOP. TOP suddenly becomes almost disgusted that a woman is touching him. The girl is representative of the woman he talks about in his song “As if nothing’s wrong,” in which it is narrated that TOP left her because his future was more important to him than she was. In this mv, TOP kills the girl (metaphorically, he abandons the girl and his desire for love) when he realizes that she is touching his artwork (metaphorically, that she is interfering with his pursuit of art). He has blood splattered on his face, and he feels the full weight of what he has done to the girl (murder in the mv, abandonment in real life) and regrets it. Lyrically, TOP talks about how everything is ruined now, because of his selfishness (of abandoning the girl to achieve his career goal), and how now that he feels no pleasure or joy in anything, it feels like he’s standing at the edge of the cliff with no one by his side.
TAEYANG. Taeyang takes ‘edge of the cliff’ quite literally. He says he barely looks at the sky (God) anymore, and instead spends more time looking at the ground (depression). He says he blames the sky (God) sometimes, and hopes that he can close his eyes in peace when this all ends. He commits suicide, and before he hits the ground the cross does first, and snaps. His relationship with God has been severed. The phrase “Sin will find you” now becomes “Sin find[s] you.” He became a sinner, and he becomes even more alone without God.
DAESUNG. The whole experience has caused him so much pain that he feels like he is being physically beaten. He says that he smiles because he’s tired of crying. He is beaten by a mob without us knowing the reason, and this is how Daesung feels as he is being attacked by people who hate him. He has one item (handkerchief) that a faceless person gave him, and I assume that this is the embodiment of the people who supported him. The mob takes the handkerchief off of him, and Daesung cries on the floor. The people have taken away the one support system he had in his life. He sees himself in the mirror and punches the mirror.
SEUNGRI. The girl is no longer interested in him because she found a different man. He doesn’t have his own verse, but he sings the chorus that repeats the general sentiment that he is alone. Rather than presenting yet another way that being an artist has caused pain and loneliness, he is representing the fear that the fans will leave bigbang for some other person, hobby, or whatever else. He destroys a car mirror (even though it’s not even facing him) because all he can see is failure in the mirrors.
But in the end, all five finally appear in a single shot for the first time, and walk in the same direction. Five lonely people coming together to form one. I guess that’s what big bang is.