This is based on a Resistance Release technique for Low Back Pain at https://massagelibrary.com/video/low-back-pain-resistance-release/
Caution:
This self-care technique is best for people with back pain that is worse when extending the back – straightening up or stretching backward. If your back pain is worse when bending forward this may not be a good exercise for you.
Do not do this if it causes pain.