While i don't want to down grade him by any means, as he is very good, he's in an open tuning.
With open tuning, the guitar is tuned differently to allow "open" to ring as a solid chord. therefore, one barre up is the next half step to the next chord and can easily be played with one finger.
this is found a lot on slide guitar (lots of blues leads are in open C or open G tunings, and some times open Em tuning).
as for breaking the guitar, the slap is really not that hard on the guitar... there's no way it would break by that