During my longest flight so far, yesterday - I lost the video screen.  It just went black - not the whole screen, just the aircraft camera video.
I'm using I Phone 6, I follow the proper protocols, Airplane mode, etc.
I was shooting video during the flight.
As the red 'losing signal' flashed, I pulled back on the right stick to get closer to home.  The red flashing stopped and I had good signal strength again.
However, as I turned the aircraft to come home, the video camera screen went black.
I still had telemtry readings for distance and altitude, so it was fairly easy to just bring it back while watching those two.
Once the aircraft was close enough to easily see, I landed without an incident.
The screen never came back onto the video camera view.

I've looked up this issue, and I did read someone say that this has been a problem since the DJI App went to 3.0.
Also, they said that to correct it, you have to turn from video to 'picture' mode.
I didn't do that while flying.
Also they say that to guarrantee that the video camera comes back online, you should back out of the main flying mode (camera), back to the 'main page' of the app, then press 'camera mode', and when you get back into the screen, the video will be back on.
I'm not doing that until someone tells me that I won't lose any settings like 'telemetry', or 'RTH' location.
Although I didn't like having to fly 'blind' it wasn't half bad.

Funny thing about the Phantom.  I like the way it looks, but a 'white' aircraft against a 'white' cloudy sky disappears pretty quick.  
Thanks!!!  Looking forward to your replies.

i'll follow this post because i had a similar situation (not that scary lol) so will keep an eye on this.

First I don't think it has anything to do with version 3.0 or whatever. Every time someone has an issue the first thing it to blame the last Go version # or the last FW update they did. Two of the things you said to reset it back, are fine to try. Switching "video/pic mode", or backing out of the camera screen to the front screen. Or even just close the app completely and then reload it. It's not going to cause you to lose telemetry, if it was already displaying. And no way your Home Point will be lost, that's stored in the drone, not your device.

I would also recommend putting the device in airplane mode so only WiFi is available. You may be getting interference from an outside source on the device. When I fly I do that as well as close any other apps besides the DJI Go app. With wifi only there are too many outside variables that can affect it.

When I first flew mine I was getting all sorts of erratic behavior because I have about 50 wifi networks overlaying where I live. Went to airplane mode and the issue went away. I have lost video or had garbled video when only a few feet away before switching to airplane mode.

This just happened to me yesterday too-- I'm wondering if it had to do with my antenna orientation and just strong interference in general-- however, it never happened before at that exact location.

WilliamM, I had a video loss today again, and I took your advice.
I tried switching from video to pic mode - didn't work.  Still ahd blank screen.
I then closed the app as you recommended, on my IPhone, I swiped the app off the screen to close it.
Then, I reopened the app, pressed camera mode, and it was completely empty of all data, numbers, telemetry, and video, as if I didn't have the controller or the aircraft on.
I did not go back into the wifi settings and reset the Phantom wifi - although it was already set when I viewed it.
So in the end, I would have been better off flying back with just telemetry of distance and height.
By turning everything off, I lost everything, and it was the longest 9 minutes of flight I've ever had, hoping that the RTH would work.
As it turned out,  it did work, and the aircraft landed on it's own safely.
Whew!
AFter all the RTH complaints here lately, it's becoming very stressful flying.

William, I appreciate the idea, I'm not criticizing you, just telling you what happened.
Do you think  I should have turned off wifi and turned it back on?  I'm wondering if the Phantom wifi signal needed to be reactivated somehow after I shut down the app.  I'll never do that again!

I am interested as well because out of 205 flights I lost phone screen after about 45 seconds yesterday. It just went blank as if the camera was off so I flew it back switched off and reset everything and it was ok for the next 5 minute flight straight after. First time this has ever happened and I was flying 1.7.9 and 3.1.2 go. I have now gone back to 3.1.1.