If you are looking for a description or a "creepypasta" style summary of the file:
"Metadata check: 28871.mp4 isn't a video. It's a broadcast. Are you seeing the signal too?"
If you want to send a text that matches the mysterious vibe of the topic:
Are you trying to , or are you looking to write a story based on this file?
If you're using it to strike up a conversation about internet mysteries, users on Quora and Reddit suggest being direct and confident. You might try:
"Just went down a rabbit hole for 28871mp4. My brain is officially fried. What's the weirdest internet mystery you've ever found?"
"They say 28871mp4 is just a corrupt file, but the distortion patterns match human heartbeats." 3. General Conversation Starters
"I found the source of 28871mp4. Whatever you do, don't play the audio backwards."