i think he just...bends it....right?
Become quicker. Harsh advice but that's all I can tell ya.
All he does is a quick standard bend with the 3rd & 4th string of the c power chord between each transition from the first chord played in the chorus to the next one,
so it could be depending on tuning C C (bend 3rd & 4th strings) G G (bend-using 3rd&4th strings of C chord)