Tsunl_9.mp4

: Bots on Reddit often generate links to .mp4 files and users frequently comment "this is a useful post" in response to helpful automated links.

: Forums for software like vMix often have threads where users thank each other for a "useful post" regarding video codecs or MP4 recording settings. tsunl_9.mp4

: "tsunl" might be an abbreviation for a specific game, software, or user (e.g., "Tsun" is a common prefix in anime-related gaming communities). The "_9" would indicate it is the ninth in a series of resources. : Bots on Reddit often generate links to