I've put up two more videos on YouTube:
Working on an Shelby Cobra, Mark Gerisch explains why he needs to stretch an edge on a power hammer rather than shrink it:
https://www.youtube.com/watch?v=LK9qmAkjOdc
Mark shows the benefits of a VFD motor on a power hammer over a cone clutch hammer:
https://www.youtube.com/watch?v=2fr-Xy5evoY