Sometimes these alphanumeric strings refer to specific re-uploads of deleted content from YouTube or Twitch.
If you can describe the content (for example, if it's an animation, a gaming clip, or music), I can likely track down the history or the creator for you. What was happening in the when you saw this name? Shin13912mp4
To help me give you the right "text" or context, could you tell me or what the video is about ? if it's an animation
It looks like "" is a very specific filename or a niche piece of media that isn't widely documented. Because this looks like a specific file name, it could refer to a few different things depending on where you saw it: a gaming clip