Not sure what I gained by listening to that video.
Now here is my opinion based on actual experience doing this on a Model-A. Each leaf was forged into shapes starting with a high carbon steel. Over time through constant pressure, the spring leaf takes on a new shape. So by pressure onto the spring over time can cause the spring leaf to be re-shaped, then contrary to what some may say, with an opposite higher force of pressure that same spring leaf can be shaped again. In this instance, the leaf has opposite pressure thus returning it to near a former shape. We have been doing this on quite a few cars for the past several years, and we have not seen any failures. Something to note however, just because a spring leaf has been re-shaped does not guarantee it will retain that shape forever. Having that mindset of a permanent repair is like suggesting a engine that has been rebuilt should last forever, -or replacing body wood should be permanent too. Everything has a life cycle, and re-arched spring leaves is no different.
More to this here....
https://www.fordbarn.com/forum/showp...38&postcount=6