A friend who goes to school with Artie finds the goodbye video from Shooting Star on Artie’s computer. Thinking it’s fake (maybe she or he recognizes Blaine or Sam from some of Artie’s other movies and just assumes it’s all acting), the friend posts it online. Artie freaks out. He had no intention of ever showing that video to anyone, but the damage is done and the video goes viral, even more so when people begin to realize that it’s real.
Now all the New Directions who are in it have to face watching it for the first time, reliving that very terrifying moment from that was over a year ago now. Even though they know now that everything turned out okay, having to face it again brings back all those feelings again. Conversations of those who were there trying to figure out why they said what they said (Blaine refusing to make an actual goodbye. Sam being more concerned about the cat in his locker than anything else.) and those who were not there facing the terror that happened in that choir room for the first time (Tina having to see what it looked like on the inside when she was stuck outside, the graduates seeing what had actually happened), and dealing with the fact that complete strangers have now seen it and know your fear.