Those production videos always seem to do a great job of conveying just how special this production is for everyone involved. That dedication worked for the LOTR films - there's a great chance that it'll work for the Hobbit films, too.
Also, from that frame-by-frame analysis:
"1:48 – 2:01 : heroic version of the melody used for the song (just sung) – this indicates to me the melody will be a theme, probably a major one, in the vein of the Shire Theme and the Fellowship Theme in LOTR"
I really hope that this will be a primary theme in the score. It sounds incredible. Is there yet any confirmation that the cue was composed by Howard Shore?