Liam Clery writes:
"7...Ke6, however, is the best move for black and it is still playable."
It is bad advice to suggest that any player of the Black pieces play 5... Nxd5? This is simply an opening blunder, leading to a difficult/lost position known since Greco (if not earlier) in the early 1600s. Moreover, rather than the Fegatello/Fried Liver, 6. Nxf7, White has the Lolli Gambit, beginning with 6. d4, which leads to an improved version (for White) of the Fried Liver. Essentially, by playing 5... Nxd5, Black is gambling with a loss. A strong player will only be too happy to demonstrate the loss to any foolhardy or uneducated player of the Black pieces.
Why play moves that are known to be bad, when there are so many moves known to be good? For instance 5... Na5, 5... Nd4 or 5... b5.
"My advice would be to not play 5...Nxd5 in this variation. Better is 5...Na5! 6. Bb5+ c6 7. dxc6 bxc6 and Black has excellent compensation for the pawn and after you complete your development, you have a favourable position. If you are not prepared to sacrifice the pawn, which is necessary in most lines of the Two Knights Defence, then play 3...Bc5 instead."
That, though, is excellent advice, which the original poster should pay attention to.
"7...Ke6, however, is the best move for black and it is still playable."
It is bad advice to suggest that any player of the Black pieces play 5... Nxd5? This is simply an opening blunder, leading to a difficult/lost position known since Greco (if not earlier) in the early 1600s. Moreover, rather than the Fegatello/Fried Liver, 6. Nxf7, White has the Lolli Gambit, beginning with 6. d4, which leads to an improved version (for White) of the Fried Liver. Essentially, by playing 5... Nxd5, Black is gambling with a loss. A strong player will only be too happy to demonstrate the loss to any foolhardy or uneducated player of the Black pieces.
Why play moves that are known to be bad, when there are so many moves known to be good? For instance 5... Na5, 5... Nd4 or 5... b5.
"My advice would be to not play 5...Nxd5 in this variation. Better is 5...Na5! 6. Bb5+ c6 7. dxc6 bxc6 and Black has excellent compensation for the pawn and after you complete your development, you have a favourable position. If you are not prepared to sacrifice the pawn, which is necessary in most lines of the Two Knights Defence, then play 3...Bc5 instead."
That, though, is excellent advice, which the original poster should pay attention to.