In most cases, "newly .mp4" is not a video of a "newlywed" couple or a "newly" released movie. Instead, it is often a designed to trick users into clicking it. The trick lies in the file extension:

You received the file via a DM on Discord, Telegram, or WhatsApp from someone you don't know (or a friend whose account might be hacked).

Be on high alert if you encounter this file under the following circumstances:

newly .mp4