When full screening a second monitor main screen switches to black?

When I have a second monitor connected and drag a video over to that side and make it full screen the main screen (my macbook) switches to that black screen picture? Why can't I have a full screened video on my second monitor and still work?

The workaround is to just drag the video to almost full size and watch but I'd prefer to know why this is happening and I'd prefer to have it full screen.

Hopefully I'm explaining this okay, any help?

 

Mountain Lion. I've been avoiding upgrading to Mavericks at fear of a few programs not working.

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I was hoping it wouldn't come to this, looks like I might have to.

Thanks for the help everyone.

 

Just a few random emulators and stuff. I'm perfectly happy with ML and keep hearing about problems with 10.9.2 so I just don't really see the point, even though I want that full screen thing. That might be the only reason I update soon. Pretty silly that even existed.

 

Ughhhhhhhh just updated to Mavericks and same problem.

VLC, drag over to second screen, full screen VLC, bam, main screen is black.

Really didn't want Mavericks but upgraded to fix this but it's still broke. Dammit.

 

The screenshot would just be a black screen.

All works well with two screens, can drag stuff back and forth, everything good.

As soon as I try to full screen an app on my second attached monitor, my mac screen switches to just a black screen. Can't do anything until I un full screen the second monitor, then as soon as I un-full screen my main screen macbook monitor comes back and is usable again.

I had this same functionality with ML, everything worked great with two screens until I wanted a full screen video.

 

Nope, pure black screen. Only can see the backlight.

I get it back by moving my mouse all the way to the left until I see it on a second (full screened monitor) and then I double clicked, or click the window and "esc" to un-full screen it.

After I have done that I have my first monitor back to normal.

To clarify when I full screen my second connected monitor only my Macbook main screen is black, I can still use the connected monitor. I thought it was an advertised feature that you can use both while full screen now? (pretty silly this wasn't always a thing and needed to be an ad feature)