Product review (3 stars): Feet + swimming noodle did the job.
The jury's still out on the performance and longevity. But I installed the feet under my obsessively moving front loading washing machine. It continued to move until it got close enough to my side wall for me to put a swimming noodle between it and the wall. Since then, it's stopped moving. The noodle seemed to be the final piece of the puzzle, absorbing the vibration of the washer moving side to side. It's stayed in place for about 2-3 weeks now.