I heard a theory about the MV that probably made the most sense, but who knows if it's right. And I'm sorry, but I'm stil not familar with all their names so I'm going to try my best to figure out who is who.
Their is a war going on and the soldiers go to the village that thr members live in to "protect" the villagers. The members discover the blue flower that is a symbol for their friendship and they learn that it can heal, but only them. At first, the members accept the soldiers and Wonho? (the guy who gets beat up) even gives one of the soldiers a blue flower to show that he wants to be friends but the leader of the soldiers doesn't like this. The old man who has the guns at the beginning is (the member who burns the money's dad). Hyungwon? then discovers that the soldier's had beat up Wonho? because of him trying to be friends with the soldier, and this pisses him off. (The guy who burns the money) finds out that his dad is extremely sick but he doesn't have the money to help him so he asks Jooheon to help him rob a bank so that they can get money for his dad. Hyungwon and the other members go to the soldier's base and burn it down for revenge. The soldiers get mad at this and take (the guy who burns the money, is it Shownu or I.M???)'s dad and when he discovers that they took his dad he burns the money in anger. Hyungwon then discovers that Wonho killed himself and attempts saving him by pouring the essence of the blue flower into the bath, which seems to hold more within it and they discovered this in their tent when they were messing around with the plant. Hyungwon gets into the bath to try and save his friend. And the heart/alien thing has to do something with the blue flower. Ummm that's all I remember from the theory. I still don't understand why that guy had a broken/missing leg, why Wonho drowned himself or someone drowned him, what else the flower can do, what's that thing at the end etc.
*This theory is not my own, it belongs to someone else. I just can't remember who at the moment.