It looks like rows of single stitch crochet but instead of doing the next row through the two loops ( of the V ) She put the stitch into the space between the 2 lower stitchs, I imagine this is a very dense fabric.

That's a half double crochet stitch worked back and forth. Turn, chain 2 at the beginning of each row and skip the "first" stitch. Work half double crochet into the top chain of each chain 2 when you get to the end of the row.

To me it looks like a straight single crochet.

Half double crochet creates more distinct ridges.

SC variations:

top left is both loops, top right is front loop only, bottom left is back loop only and bottom right alternates between front loop and back loop