Open the file in VLC Media Player and go to Tools > Codec Information or Properties to see if the "Title" or "Comments" fields contain the film's real name.

Many digital cameras (like certain Panasonic Lumix models or Sony units) use a prefix like "P," "G," or "DSC" followed by a four or five-digit sequence.

Use services that can identify a film by listening to its audio or analyzing a screenshot.