The filename format Received_[NumericID].mp4 is the standard naming convention used by when saving a video to your device.
This file likely originated from a video sent or received in a Messenger chat that was either manually saved or automatically cached by your app. Why did it appear "out of nowhere"?
To prevent this in the future, go to Messenger > Settings > Photos & Media and toggle off Save on Capture or Save Photos and Videos .
Most users find these files because of . If your Messenger app is set to "Save Photos and Videos," any media sent in your active chats will download to your phone's local storage. Even if you don't remember saving it, a quick tap or an app update might have triggered the sync. Is it a virus?
If you’re uneasy, run a quick scan using a trusted app like Bitdefender or Malwarebytes.
Search your recent chats for a video. If the ID matches a video you recognize from a friend, it’s safe.