Serendipidy. As I understand it, turns are measured BETWEEN foot placements, and refer to the feet rather than the rest of the body (which often turns less, especially on backward movements).
Looking at Alex Moore's descriptions, I see where you might have got the description of 3/8 turn between 1-3 (Man) [the ISTD syllabus is just a little more detailed]. You're right about Step 3 moving straight back containing no turn (Moore's description is "...3/8ths of a turn between 1 and 3, and 3/8ths of a turn between 4 and 7"--notice there's no turn between 3 and 4).
This would explain why the lady's 3/8 turn is described as between steps 1 and 2. Her (heel) turn is complete by step 2.
On the man's step two, however, perhaps you might want to look at the feet specifically--the upper body in the demonstration may hardly rotate at all at this point. This isolation between the upper part of the body and the feet is what I find especially beautiful about much of standard/smooth dancing.
Hope this helps. In the meantime, I'll pursue your suggestion and check out Luca and Hilton--ultimate models of standard technique, IMHO.
Cheers.