The double moss stitch or double seed stitch, as demonstrated in this how-to video, is just a knitting pattern alternating between two knit and two purl stitches. It's very easy to do, but comes in two varieties, American, with the right hand, and English, with the left hand. Watch this video knitting tutorial and learn how to do the double moss stitch.
Have an iPhone? Check out all 200+ new features coming in iOS 13.