How to open padlocks with a pair of nut wrenches

Mr. Gear shows how to break a padlock by levering a pair of nut wrenches between the shackle, which breaks off a chunk of the padlock body. I don't recognize the brand of these padlocks, so they might be made from weak metal. It's probably better to shim a padlock with a piece of an aluminum can, as shown below:https://www.youtube.com/watch?v=fRjNnnLOpmE