If you're trying to open a file and it keeps opening the wrong apps, you may need to change your file extension. Here's how ...

How to view file name extensions in Windows Vista and Windows 7. ... In this screen, put a check mark in the checkbox labeled File name extensions. You can now close Windows Explorer.

Expand the Name & Extension category as shown in the image above.; Under the file name field you should see a checkbox labeled Hide extension.Uncheck this box to have the Mac OS display this file ...

Double-click the icon labeled as ... Click the link to open a configuration dialog box. Now, type ‘.mp4’ in the ‘File Name Extension’ field. Also, enter ‘video/mp4 ...