Why can’t I get picture in full screen mode when I’m watching videos on the Internet when I can get sound still? 
A few different scenarios could lead to this problem. Read through these suggestions and use them one at a time until you solve your problem. Try the first solution first as it is the most likely one.
Full Screen Mode and WMP
When the full screen mode is used with WPM or Windows Media Player, the player is sometimes actually bumped out of the screen. Hence, you can hear the movie but you can’t see it. The thought of that just makes me cringe with annoyance so I can imagine how you are feeling.
Let’s see if the following adjustment works to fix the problem:
Open Windows Media Player>Select Access Application Menus>Select Tools>Select Options>Select Performance>Select Advanced> Select Video Acceleration>Turn off the “Enable full screen mode switch” by removing the check that appears in the little box in front of it. Alternatively, if the “Enable full screen mode switch” isn’t turned on, you can place a check in the box and see if that makes the problem go away.
Troubleshooting Full Screen Mode Errors
It might be necessary to change the video acceleration in order to get full screen viewing. To do so, use this path:
Open Windows Media Player>Select Access Application Menus>Select Tools>Select Options>Select Performance>Select Advanced>Select Video Acceleration>Move the slider to decrease or turn off the acceleration.
Requirements for Viewing Videos
In order to view videos, it is necessary for you to first install the proper program onto your machine. For example, this problem of no video while audio still works can occur if you are trying to view the video through Windows Media Player but the video has been formatted for use with a different player. Before you install a new program, try these strategies first:
- Update the Video card drivers.
- Install a video converter such as Windows Media Encoder, Windows Movie Maker, or Microsoft Expression (all of which are offered by Microsoft.)
Video Playback and Viewing
If you know which extension is attached to the video that you are trying to view, you can determine whether or not you have the correct player for viewing. Here’s a list to help you in the future.
- The .avi file extension can be opened with “Windows Media Player.”
- The .ram. file extension can be opened with “RealPlayer.”
- The .mov file extension can be opened with “QuickTime.”
- The .qt file extension can be opened with “QuickTime.”
