This.
There is almost always something that precipitates a fight, even if it is just harsh words spoken in haste. Whilst I think MWM is exaggerating a little bit, it's would be quite delusional to think there weren't a few Thai's who'd take any excuse to put the boot into a Farang. Especially in the tourist area's.
So basically Bazza the Bogan and Charlie the Chav act like they do back home, call the bouncers counts, threaten the tuk-tuk drivers thinking they are invincible. Pretending they are tough. But the bouncers don't think they are as funny or as tough as they think they are. Violence ensues.
Put simply, Thai's are culturally wired not to start fights (loss of face) but can be very easy to piss off and once that happens, they have the excuse they need to save face (as it's you're fault they hit you, Thai logic but it is Thailand).