In case the plot is confusing, here is the breakdown.

Q. Whats with the static and the whirring and the tape nonsense?

A. Luhan's life is represented by a VHS cassette that plays throughout the day and rewinds back to the beginning when he sleeps hence the static in his dreams and the whirring. He sweats because he fears waking up and reliving the same fate he's tied to everyday. His life constantly pauses rewinds plays and ejects at random moments so he has a hard time facing it.

Q. Who is Xiumin?

A. He is Luhan's second logical boyfriend but stole him away from Sehun while they were still in an ongoing relationship. They dated for the next three years into high school, with Luhan never knowing he was only a fling.

Q. Who is Sehun?

A. Luhan's first boyfriend. They started in middle school when Sehun finally took notice of the boy, but didn't get far when Luhan cheats and runs to Xiumin's open arms.

Q. Explain the scene with Xiumin and the memories?

A. Luhan's life is dream-state like and it twists harder the more he fights against it and realism gets farther from his grasp. He walks into school and it's no longer his school but a hall of all the painful things that has ever happened to him. The people he met and the words he heard. All 12 members are standing before him but in twisted sick forms as if mocking his pain and Luhan gets angry and stands up for himself when all these years he has been taking the backseat and taking it all in. He approaches Xiumin and is faced with the same truth that he had to relive everyday, but the knife only dug deeper every time he had to face the truth. He really loved Xiumin but felt regret and shame for being so naive and leaving Sehun. He pulls at Xiumin's tape reel which destoys it, the same effect a Horcux would have, leaking the memories inside the tape before dying.

Q. How did Sehun end up back with Luhan? What on earth happened at the end?!

A. Right when Luhan ruins his own tape by tweaking Xiumin out of his life, he falls to the ground and static resumes, signifying the end of his life once again. He's afraid that everything would rewind and be back to the way it was before. But he wakes up in shock, back home and in bed with Sehun, wondering what on earth happened. But the idea got farther the harder he tried to remember. (Like the way it usually happens when we wait too long or think too hard about what we dream about right when you wake up) He only remembers Sehun in his memories, the false memories that have been implanted by Sehun that nothing ever existed but the two of them.

Q. So?

The good outcome of this ending is that Luhan no longer feels or remembers pain, as it is the life that he no longer has to live through. Sehun has torn out Luhan's old film completely, not destroying him, but replacing it with a new idealistic life that he has created for Luhan. Hunhan has a "happily ever after".