The .mp4.mp4 naming convention is a common tactic used in file-sharing communities. It often serves two purposes:

You likely just experienced a jump-scare.

The video is designed as a "trap" to startle unsuspecting viewers. It typically follows a specific pattern:

While the video itself is generally just a prank intended to scare you, files shared with double extensions can sometimes be used to disguise malicious scripts (e.g., filename.mp4.exe ).