Scotch 4...Qh4

Just watched GM Delchev's video Learn to Play the Scotch Game: 4...Qh4 Refuted
https://www.chess.com/video/player/learn-to-play-the-scotch-game-qh4-refuted

As a 4...Qh4 player myself, I was a bit worried by the title. Needlessly as it turns out.

Delchev concentrates on 5 Nc3 Bb4 6 Be2 Nf6(?) 7 Nf5, whereas after 6...Qxe4 7 Nb5 Bxc3+ 8 bxc3 Kd8 9 0-0 Nf6, he only gives 10 Be3 Re8 11 Re1 Qd5(?) 12 Qc1 Qf5 13 Qa3 d6 14 Rad1 (as in Azmaiparashvili-Hector, San Sebastian 1991).

In fact GM Gutman dealt with this line nearly twenty years ago (2001), giving the improvement 11...d6! and if 12 Qc1 Qg6 or 12 Rb1 Re7!.

GM Barsky looked at this line too (2009), adding 11...d6 12 Rb1 Re7 13 Bf3 Qh4(?) 14 Nxd6! and wins. But 13...Qc4 is much better, when 14 Nxd6 cxd6 15 Qxd6+ Bd7 16 Bg5 Rc8 is just unclear.

So while 4...Qh4 may not be best for Black, Delchev certainly hasn't refuted it.

yes, you do need to be worried.

Lanes "How to play the Scotch" points out there is a very sac on d6 by White not mentioned by Gutman

Which Nd6 sac do you mean? Lane has two: 9...a6 10 Bf3 Qc4 11 Nd6 and 9...d6 10 Nxd6.

Neither comes in the critical 9...Nf6 line though.