Hi Jim,
the ripples you are seeing at the back of the feet is the result of the carpet stretching backwards in front of the feet. It's similar to a rubber band effect, in that the stretch at the front is actually helping to pull the carpet forward, contributing to the stretch. The principles that the stretcher uses is called Vector Mechanics and has been known of for centuries, it just has never been used in the carpet industry before. As far as stretching only 3 feet of the carpet, that is truly not the case. The carpet is stretched evenly all the way around the room and the short clip with the kicker shows the results. The adapter has been used out in the field daily for 8 years for installation, re-stretches and re-installs and has worked flawlessly. Also, there has not been a single recall due to an under stretched carpet that has rippled and many of the rental units have had the carpets cleaned several times since the installation.
Thank you for weighing in, Jim!