Why it worked
The video leverages the reunion of two martial artists after a long time, creating anticipation for a test of skill. The humor derived from the instructor's exaggerated reactions to the master's powerful technique likely contributed to its shareability.
Summary
Two martial artists, one a "Yetbeop Taekyun Master" and the other a "Team MAD" instructor, reunite after five years to test their striking power. The master demonstrates his technique, leading to a surprising and painful outcome for the instructor.