I weight my selvedge threads separately almost always. I learned from Jim Ahrens that you could use stronger threads for the selvedges when you want to weave with fragile warp threads. I’ve shown the knot I use to hold the weights in many workshops and in two of my books, but it is wonderful to have a video so you can see the motions of my hands. You might still need the diagrams in the books, but I think this is a big help. The books are: Weaving for Beginners and Weaving & Drafting Your Own Cloth. Both have a whole chapter devoted just to selvedges.