4...Nf6 5.e5 d5 6.Bb5 Ne4 7.Nxd4 is variation 3 of 6 in the Scotch Gambit course, a intermediate opening course for White (ECO C44). It runs 21 moves and begins 1. e4 e5 2. Nf3 Nc6 3. d4 exd4 4. Bc4 Nf6 …. Black develops the knight and attacks e4. White pushes the pawn to e5. Black hits back with 5...d5, and White pins the c6 knight with the bishop. White then wins back the pawn on d4 and chases the e4 knight with the f-pawn. In the lesson every move is explained on a board and then drilled; it is free.
Move by move
1. e4 – White takes the centre.
1... e5 – Black claims an equal share.
2. Nf3 – White develops and attacks e5.
2... Nc6 – Black defends e5.
3. d4 – White opens the centre.
3... exd4 – Black takes.
4. Bc4 – The Scotch Gambit. The bishop aims at f7.
4... Nf6 – Black develops and attacks e4.
5. e5 – White pushes and chases the f6 knight.
5... d5 – The best answer. Black strikes the c4 bishop and opens lines.
6. Bb5 – The bishop escapes and pins the c6 knight.
6... Ne4 – The knight jumps to a strong central square.
7. Nxd4 – White wins back the pawn. Material is level.
7... Bd7 – Black breaks the pin.
8. Bxc6 – White trades on c6 and damages Black's pawns.
8... bxc6 – Black takes back toward the centre.
The lesson goes on for 5 more moves, each with its explanation.