12379147-1440p.mp4 Instant

: Right-click the file, go to Properties (Windows) or Get Info (Mac), and look at the "Origin" or "Description" tags.

: Look at your browser’s "Downloads" tab to see the website you were visiting when the file was saved. 12379147-1440p.mp4

If you are trying to figure out what is in this specific video: : Right-click the file, go to Properties (Windows)

: If the video is a specific scene (e.g., a nature landscape or a tech demo), a screenshot of a frame can be uploaded to a reverse image search engine to find the original source. : Right-click the file