In many scenarios, particularly when encountered on unfamiliar websites, a "SmilyMP4" file is not a conventional video file but a disguised threat.
It frequently appears in online forums or "free download" sites where it is presented as a downloadable video (MP4) but is actually an executable file ( .exe ) designed to install malware. smilymp4
I can provide more targeted safety advice based on your situation. File checker: Scan files for viruses - NordVPN In many scenarios