From the looks of the video I would take a yard of fabric (guessing here) and cut 3 inch strips by WOF. With wrong sides facing put two strips together and sew from selvage to selvage vertically directly down the center. Fold both individual top pieces inward to meet the seam you have sewn. Press. Now flip it over and do the bottoms the same way. You can make any size you want, it doesn't have to be 3 inches wide. Insert your QAYG blocks and stitch the edges down to hold blocks in place. Does this seem reasonable?