I don't particularly remember watching this youtube tute but this is close to what I did. My handwritten directions say 7" x 7" for cloth and batting. 7" x 4" for binding.
Press binding in half. Sew to outside fabric. Fold and iron to back, leaving 3/4" in back.
Place batting on back of cloth, under binding. Sew.
Turn case so the fronts face, sew edges.
Turn right side out.
https://www.youtube.com/watch?v=Irqg7EWPnqE
Is this what you were thinking of?
[ATTACH=CONFIG]536779[/ATTACH] Edited to add picture.