If anyone is still having this problem with playing videos Windows Media Player Plays All Video In Full Screen try holding down FN = Function key and F8 at the same time it fixed my problem.
I should have added that I was playing the video at the time i held down those keys
I know the keys switch between monitors at least the way I have it setup desktop external monitor since my laptop lcd screen went blank.
I use to have the problem when I rebooted the PC the desktop monitor went into power save mode very frustrating since the laptop LCD screen wasn't working either so I found out you have to wait until the operating system loads then the second monitor turns back on.
Another option is right around the time your PC reboots press function key (fn) and F8 at the same time and the 2nd monitor you have hooked up comes back on.
The reason I wanted to post this info is because someone else might be having these problems and if you don't have a working LCD laptop screen but you do have a desktop monitor hook it up because other then buying a new screen for your laptop seems to be a easy workaround to be able to reformat and reinstall your operating system if needed.
