This video features 6...Qc7 in the mainline of the Stonewall, a good move since after the obvious 7.Ngf3, White turns out worse in all lines. Matt suggests an alternate development of pieces including Nh3 and Qf3.
The game Van Vliet-Znosko-Borovsky, 1907, is very important for White and Black to be aware of. Matt found this game in the back of Aron Nimzowitch's 'My System'. It is the best chess book ever written, but computer analysis disagrees with Nimzo's assessment of a critical line in this game.