Beaded welt

I want to make Charles Gandy’s sock called “Christmas Tree Socks” and it calls for a beaded welt. I’m not familiar with this and wonder if someone can suggest a video or tutorial? Is the welt knitted separately and then somehow placed on the sock?
Thanking you in advance for help, advice.

It looks like it’s knitted as part of the sock:

See if the pattern gives directions for this either at the beginning or the end of the sock pattern. It’s a little hard to tell from the photo but the idea is like a picot hem:

It may be even simpler than the video in that it may be just a purl row on the knit side instead of the k2tog, yo at the turn of the hem but the idea of the turn is the same.

Thank you for your help, really appreciate it. I’ll look at the video.