The Best Christmas Chord of all

There's been plenty of videos and essays about what makes chords 'Christmassy', but that's not what I want to do here. I want to talk about a single chord in a single carol.
The 'Word' from verse 7 of Sir David Willcock's arrangement of 'O Come, All ye Faithful', often recognised as the best Christmas chord of all time. But what makes it so great? This video tries to find out.
Merry Christmas!
P.S. - You can get your 'Word' shirt from Thread Underfoot here: www.redbubble....