a piano trap

where is the trap?

The trap is that that the Black Knight that was controlling d4 gets traded off, then the White Knight is given a strong central outpost.  At least that's what it seems to me that he's talking about.

fork the queen and rook

I prefer black - two bishops and white doesn't have much after ... Qd8

Coincidentally, I really like 6. Be3.  After 6. ... Bxe3; 7. fxe3; followed by 0-0, I like white's position, because of the central block (Pe3 controls d4 and f4) and the rook has the open f-file.  Just my opinion, though.

Perhaps he means that the Knight is threatening both the Queen and the fork on c7.  However, this can be prevented by Qd8 (although I would prefer white's position).