4...Be7 5.Nxd4 is variation 6 of 6 in the Scotch Gambit course, a intermediate opening course for White (ECO C44). It runs 15 moves and begins 1. e4 e5 2. Nf3 Nc6 3. d4 exd4 4. Bc4 Be7 …. Black plays the quiet 4...Be7. White simply takes back on d4. Both sides develop and castle. White has more space and easy play in the centre. 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... Be7 – A quiet move. Black gets ready to castle.
5. Nxd4 – White takes back the pawn. Material is level.
5... d6 – Black opens the c8 bishop.
6. O-O – White castles.
6... Nf6 – Black develops and attacks e4.
7. Nc3 – White defends e4 with the knight.
7... O-O – Black castles.
8. h3 – A useful waiting move. It keeps Black's pieces off g4.