Quite interesting, and yet I've been using vim daily for a few years now. The learning never stops :)

Is this how SnipMate, UltiSnip etc work under the hood?

>The learning never stops :)

Totally. I wrote a book on it, and I still keep learning :)

>Is this how SnipMate, UltiSnip etc work under the hood?

No idea, I don't use these. I'm generally trying to use as few plugins as possible.