KalamaQuilts

Preface by saying I didn't watch the video, but I've done this on leader ender quilts. In the photo attached you can see what well washed looks like, the red square with blue surround., Because they are both cut on the bias they don't unravel, just softly fray. I use a zigzag on the losenges quilt that tacks back and forth on the cut so it barely fluffs. I'd show a photo of it but I buried my little doxies in it last fall.

I recommend the process for fun quilts.
I guess it doesn't show much on the losenge quilt, but all the corners on each block are stitched this way. Then I trimmed off the back triangle.

I also did it on a bullseye quilt with three stacked heart shapes using one of my fancy stitches just inside the fabric, it frayed up softly and is a favorite quilt, but again, it is all bias so the technique works well.