While I was putting the binding on the Crown Royal Memory Quilt, I decided to snap some photos of how I do my mitered corners (so which I had a way to video this). But here goes and hope it is helpful.
I use 1 1/2 inch strips for my bindings, all sewn together. I cut them in straight strips (no bias cut) and then sew them together with the mitered technique (picture of that when I finish the binding below). I start about half up on one side of the quilt, sewing the binging right sides together to the front of the quilt top, leaving a "tail" not sewn down. I don't fold my binding in half, if I did, I would make it at least 2 inches wide. I sew with a 1/4 inch seam.
When I get to the corner, I mark the end of the side at the 1/4 inch spot and sew to the pin, do a back-stitch and end my sewing.
Then taking the quilt out from under the needle, I fold the binding strip at an angle from the corner.Then holding that fold in place, I fold the strip back down over the fold.
Sewing from the edge, back-stitching to hold the thread, I simply continue sewing until the next corner and then do this process all over again.
When the corner is binding is turned to the back, the mitered corner appears.
Knowing how much continuous binding to have is sometimes the hardest part of the process. Always have a little extra for these mitered corners since you will be folding some of the strips over itself. When I get close to where I began, I end my sewing and then see where I need to add my finished mitered seam.
I leave a tail on both ends so that I have plenty of room to work with the pieces.
I lay one piece down at a angle, just like the corner, with a fold and then lay the other strip over that. I finger press that fold to so it hold's it's fold better.
Where these two intersect is where I want to sew. I place a pin to hold it in place on the side where I want my seam to be.
Now, moving the quilt top out of the way, I lay these two pieces down to sew across the angle of the pin, keeping right sides together.
Trim away the "tails" leaving 1/4 inch seam and simply place back on the quilt top. It should fit perfectly in the space you have left. Sew it down and finish off.
Normally I hand stitch the binding down to the back, but this time, I folded up a bit of the strip and sewed it down on the previous stitching where I attached it to the front. I used black thread and it worked perfectly and I have it done very quickly.
This is a queen size quilt, made from Crown Royal bags. I purchased the yellow fabric and the purple fabric for the wide strip on the boarder. All the other purple fabric came from the bags, even for the binding. I used 32 bags for this quilt. I posted about the process of preparing the bags and the pattern on A Purple Cloth. It took a little over a month to make.