As discussed in the preview, the group was inspired by Breaking Dawn - Part 2's big twist.
"I didn't think we would actually do a follow up Twilight HISHE, but then Breaking Dawn - Part 2 came out and did something that just screaming opportunity, so we're going for it," one of the artists explained then. "I think the first 'How It Should Have Ended' of Twilight really sums up our opinion on the franchise, but then Breaking Dawn - Part 2 did this thing that I think is sort of questionable."
As with their first Twilight spoof video, the Breaking Dawn - Part 2 one alters the ending a bit to reflect an entirely new course of direction the events could have taken.
Without spoiling anything, let's just say it's not something I even considered when watching the big finale, but come to think of it, it does at least raise some questions. Although, the Twilight faithful might have some deft responses to those very questions as well. It's too hard not to spoil and discuss, so just go and watch it already!