냐면

as for what it is — here it is

A speaker's device for setting up their own answer: they pose the question and immediately answer it, so it comes out as as for what X is... or here's the thing. The examples are almost all fixed openers — 뭐냐면 "what it is, is...", 어디를 왔냐면 "where I've come to today is...", 중요한 게 뭐냐면 "here's the key point". It is a stalling and framing move that buys a beat before the reveal, which is why it saturates YouTube narration. The most famous member of this family is 왜냐면, why it is, i.e. because.

Register: spoken narration, very common on video