MP4 files won't autoplay

[jimbir]

When I try open an MP4 attachment in my emails a window pops up asking me what I want to do with this file? I have VLC selected. When I hit the okay button, the media plays. I've contacted Yahoo mail, Firefox and Geeks To Go asking them why the MP4 files don't open automatically. I followed all of their suggestions for option settings but the files still do not automatically open. I've even tried different media players without success. Does anyone have any suggestions I could try?

TIA Jim Birke

[Hitchhiker]

There are two possibilities here. Either the file has another extension which you can't see, or there's some kind of corruption in the operating system.

To check in Windows, go to Folder Options ---> View (tab) and remove the checkmark from "Hide extensions for known file types". Apply /OK to exit. Here's a pix showing that setting on my Windows 8.1 machine.


(click to enlarge)

If the file has another extension you should be able to see it now.

If it still looks like an mp4, open an elevated command prompt in Windows and run sfc /scannow to check for file corruption.