Why it worked
The video's effectiveness likely stems from its raw, unfiltered depiction of a real-world, high-stakes event, capturing the fear and urgency of the situation. The on-screen text and watermark provide context and attribution, respectively, without detracting from the immediate impact of the visuals.
Summary
This video shows students hiding in a classroom during a school shooting in Thailand, with gunshots heard in the background. The on-screen text provides a warning about viewer discretion and identifies the event as a school shooting where gunshots were heard while students hid.