Can someone explain this chess position to me?

The Game Room
1

At 4 minutes 41 seconds in this game, Alireza Firouzja moves his knight to G6. Why does Magnus Carlsen not just take Alireza’s rook at F6?

I must be missing something obvious, which is par for the course with me and chess.

Here is the link http://www.youtube.com/watch?v=rJtyQLkmRsU&t=4m41s

2

White currently has two defenses for Black’s king/queen fork Nf4+: Bxf4 and exf4. Bxf6 would remove both of them: the bishop would no longer control f4 and the e-pawn would then be pinned by Black’s rook, making exf4 illegal.

3

Ah, thank you!