Most hand binding tutorials treat the corner as the easy bit. You stitch up to the miter, turn, and carry on down the next side. The fold stays closed because the iron said so. Sherri McConnell stitches hers shut.
That is the reason she filmed this one. She'd already put out two binding videos that take you through sewing the binding on by machine, and the hand finishing was the part she'd never shown. The corner trick she thinks came from her grandmother, though she isn't sure anymore. She's been doing it that long.
She takes a stitch just before the miter, goes down underneath the whole fold, and comes up at the top of it. That same stitch pulls the miter closed. Before, a small gap sat right at the corner, and a gap is where a binding starts to come apart.
Her stitch spacing changes with the quilt. On a wall hanging she's at roughly 3/8 inch. On a baby quilt, or anything going on a bed, she tightens to a quarter inch. She worked that out the hard way, restitching bindings on her own kids' quilts after they let go.
The setup around it is worth a look as well. Wonder clips go on every 1 1/2 to 2 inches all the way around, so the miters are already crisp before the needle arrives. Her thread is a neutral that passes for a match against everything, because nobody wants to rethread halfway along a scrappy binding, and it all lives in a small bag with the scissors and two needles ready in it.
The video has passed 117,000 views since 2021. Most of us were never taught the corner at all.
If you want the same finish written out from the first stitch to the last, with the measurements and the order of it, we wrote that up here: how to hand bind a quilt with perfect mitered corners.
Sherri's channel, where those two machine binding videos live as well, is A Quilting Life.