This bind-off is probably one of the stretchy bind-off I know to bind-off ribs.
It is perfect for bind-off stitches on toe-up socks.
How To Do the Lori's Twisty Bind-Off ?
Explanations step by step for the Lori's Twisty Bind-Off
Step 1: Knit the first stitch.
Then step 2: Rotate your needle counter-clockwise, the thread will be in front of your work.
Step 3: Purl the next stitch. Pass the previous stitch on this one.
Then step 4: Rotate your needle clockwise, the thread will be in back of your work.
Finally, step 5: Knit the next stitch. Pass the previous stitch on this one.
Repeat steps 2 to 5 until you have binded off all the stitches.
This method has been created by Lorraine LeGrand, you will find more informations on Ravelry.