My MP4 videos were playing very well on my MacBook Pro (Mid 2014) OS X El Capitan with Flash Drive, but since I imported and tried to open a Window Media Player video by mistake, a window opens up saying "mp4 file cannot be opened because it is from an unidentified developer".
So now I can still play my .MOV files but not the MP4. Any possible solution?
Thank You!
If you hold the Control key down whilst clicking on mp4 it should now give you the option to Open.
That actually worked! Thank you Eau Rouge, for such a quick reply. However, that means that every time I want to play a MP4 file I have to do that, when before all I had to do was double click on the file; that was sooo easy. Is there by any chance a way for me get that wonderful functionality back?
Thanks a million for your help.
If you want to change the default application that opens your mp4 files try this.
Select/ highlight one of your mp4 files then press Command-I to get the Information window.
There you will see in the list Open With, you may have to click the disclosure triangle, now click on the drop down menu
for a list of all the apps you have that are available to open mp4 files. In the list you will see the Quicktime Player app
which is the macs own video/movie player if you select this and then click on Change All, all your mp4s will now open using QuickTime. You may have another video player that you may want to choose, perhaps it has more functionality
than QuickTime, so please choose one that suits your needs. Have a look at the screenshot below, but note the apps you see available for me will not be the same for you, its to give you an idea.
Eau Rouge, again thanks a million! You really helped solve the problem... genius! Everything you suggested worked. 🙂
mp4 file can't be opened because it is from an unidentified developer
