That's cool, I didn't know he had youtube.
http://www.youtube.com/user/mchimonas#p/u/9/u94WsKf6JRo
He pretty forthrightly says what the limitations of the Mapp gas are in this video. Including such stuff as leaving gaps in the penetration of silver into the joint as a result of the multi step process used in using the colder torch, etc...
The process shown wouldn't be state of the art even if the correct torch were used.