Brian just tweeted an hour ago saying:

OMG~! Forgot we had to film 2 episodes today so I'm about to drop dead from a heat stroke and exhaustion.... 오늘은 2회분을찍어야해서 너무 너무 지친다... ㅠㅠ

Oh my. It must be hard for him to film 2 episodes in one day and maybe he haven't been sleeping well these days so thats why he feel like he's gonna die.
I guess korea's weather now must be really hot like most of our countries.
Lets just hope he drinks more water and rest well in order to perform his best in shows and programmes.

Reported by Ting18♥@dailykpopnews
Source: brian's twitter