I can't see why its brilliant. I know it's there, but I don't see it.
Nxd4 is just a queen sacrifice that leads to a huge attack, following up Bxd1 with Ne6. But it's very complicated. Click on analysis (the three horizontal lines in the lower left corner of the diagram), and you can see all the lines.
Of course, your opponent had no idea about any of this, and played Nf5 instead, which wins back nothing and just loses immediately. Proving that he just blundered the queen, not sacrificed it with purpose.
And what was that last Nh6 move? I suspect that white must learn how the pieces move.
I am sure it's obvious to a good player, but I am still new. It seems as though it favors black.