Chess.com

i agree with karpooof.

aniaml: if i have the same position as you, i think white answers e5 with Nd5 attacking the Qc7. Then black won't be able to play Nf4 bc Nd5 is controlling that square. After let's say Nd5 Qd8 Nf5 Bxf5 exf5, the white knight on d5 is amazing, and the black king is stuck where white will soon start attacking (with f6/g6).

At 21:18, why not ...e5, gaining a tempo on the white knight and setting up a nice outpost on f4 for the black knight?

Good and instructional as far as it goes, but chess is not an exact science (do not let the Algebraic Notation fool you!) any more than weather forecasting is (a misnomer - it is an art and not a science - the same is true of chess)!  Some of these lines presented here can be refuted over-the-board if the player is good enough and has enough time on his clock!  No matter how you slice it - the Najdorf Variation of the Sicilian Defense still remains one of Black's best defenses against White's King Pawn Openings, and 6. Bg5! is one of White's sharpest tactical retorts!   

At 15:03 min Kg8 is abig mistake

because after BXNe5,dXe5...white plays Qg6+ winning the game,after Kf8,O-O+, Bf6, RXf6+