Preposition. Among. Note: at this point, “amongst”–like “whilst,” “amidst,” and “oftentimes”–is quite prevalent in “unofficial” writing, such as blog posts, Facebook, Twitter, and student writing, but has not yet penetrated the American mainstream. Give it time. “A wicked straight-faced satire of despair and false hope amongst the hip.” (Michael Sragow, The New Yorker, October 10, 1994, capsule review of the film “The New Age”)/”Narcissism an epidemic amongst Millenial students.” (Blog post, March 3, 2011).
notoneoffbritishisms.com 
The cited blog post seems to be by someone in Sydney. Can’t he be excused?
“Amid” doesn’t often sound right.
Well because you’d use among, not amid. Among is to amongst as amid is to amidst.
I see it more and more, but I don’t hear it on radio (NPR). My impression (only my impression) is that it’s becoming more common in the US than in GB.
Whilst, amongst, amidst, are all unusual in Britain,though we do know what it means.
I always assumed that “amongst” and “whilst” were western hemispherical corruptions, harking back to the vaguely recalled residue of how Columbus declaimed over a Big Mac in the Big Apple. There’s something a bit pansy about concatenating -st to the end of perfectly serviceable prepositions.
Perchance, I’m up the creek?
I didn’t think this was a NOOB at all (but I may be wrong). I use it quite frequently and feel it is very natural to use in medical documentation (East Coast USA), ie. “amongst these differentials, MS-related optic neuritis seems the most likely”. But maybe that’s a medical culture peculiarity