: Use a universal media player like VLC Media Player , which supports almost all video codecs.

: Look for a brand name or logo near the number.

If you have a file named 41724.mp4 on your computer or device:

: If you don't know what's in it, right-click the file, select Properties (Windows) or Get Info (Mac), and check the "Details" or "More Info" tab to see the file size, resolution, and creation date.