file can’t be opened because it is from an unidentified developer

[Fez Vrasta]

Hello,

lot of times it happens that when I try to open a downloaded file I get:

<filename> can’t be opened because it is from an unidentified developer
​

The problem is that it happens with mp4 files, text files and so on...

Why does it happens? They are not "executable" so I wonder why such kind of protection kicks in.

Thanks!

 

[Fishrrman]

Open the "Security" panel in System Preferences.

Click the lock icon on the lower-left and enter your administrative password.

Now, look at the "Allow applications downloaded from" area.
You need to click on "Anywhere".
Then click the lock icon to lock it, and close System Preferences.

Does this change anything?

 

[Fez Vrasta]

No, I've already enabled it. I must "right click it" and click on "open file" to make it play it by quicktime/vlc...