The orchestra sounds great but someone needs to tell the cast not to sing louder than beautiful. So much screaming makes it sound like a high school production of...I don't know what, but I don't want to hear it. This production is evidently one big belt-off.
Rachelle Ann Go sounds like she is singing it properly, so I too do not understand how she blew the last note.
As for the belting, they are in a relatively small space, so naturally everything sounds louder. That said, the style of singing doesn't sound significantly different than previous incarnations of the show.
I saw Rachelle perform this role in London and she held the same note to the end; here, she fell off the note and tried to pass it off as a "run" (as they'd call it on American Idol).
Listen to the same line here for comparison, at about 4:08:
You're listening to two parts of the same song. At 4:08 in that video you linked to, it's the second chorus, which goes into the "Dream..." part. But in the sitzprobe video it's the first chorus, which is written to do exactly what she did; hold the note and then trill down to the lower note. It's at 2:36 in the video you linked to.