Before you cut loose on the video and attempt the tutorial steps, a little reminder, and hopefully a helpful hint.
Most of us when we begin drawing scribble a lot, make random lines, that don't appear to make much sense, but as we continue the lines become more formed and patterned, and over time actually start to look like what we see.
What I would like to point out in this tutorial as I did a previous one is that even though it's pen and ink for the medium, this can also be done with pencil.
What the good gentleman is doing is basically using various methods of hatching to create the textured look.
In 3D Design we use photographic images to act as the base for our textures, but that also could just as easily be a drawing. The end result is what we're after more than the inbetween steps. If you reach the end, which is a satisfactory outcome...the look you desire, then it doesn't matter what middle steps you took, because a rose is still a rose, no matter where it grows.
In short, what I'm saying is, that anything you observe can be averted to what you prefer by using a little imagination.
So, in this case, we will use pencils, if that's our medium, instead of ink. Just make sure that you apply the same principles of value...light and dark...as your draw your hatching variations.
How to Draw or create realistic textures in 9 different ways as part of drawing fundamentals and basics. This tutorial provides simple but powerful tips on creating texture and covers a variety of textures that can be used to depict many different kinds of surfaces and materials: fur, wood, scales, wool, carpet, hair, rocks, stone, tiles, sponge, etc. Its really up to your imagination :-)
Note that the same principle whether you are painting texture, sculpting texture, or whichever medium you use to create art texture or texture in art. See my other videos on pen and ink drawing tips, tricks, tutorials and techniques :-)