I did try using the Elmer's School Glue instead of pins and it's even easier! Do everything the same as the tute but after pressing the 45 degree angle, lift up the top border piece and put a small line of glue along the underside of the pressed edge. Lay it down, make sure it lines up, and press to heat set and dry the glue.
Open it up and sew on the pressed line. The glue will wash out when the quilt is laundered.