After I upgraded to Windows 8.1 I noticed that my Xbox 360 wouldn't stream video files even though it had no problems under Windows 8. After trying every solution on many many forums none of which worked, I gave up for a while, then I updated another laptop with win 8.1 whilst doing so I noticed an option:
Media Streaming Options
which I think was Media Stream in Windows 7, after finding this it was easy to click the allowed option and it worked instantly.
To get Media Streaming Options in Windows 8.1, press the windows key (Windows key - Wikipedia, the free encyclopedia) - then just type Media Streaming Options you don't have to type the whole word it should show on the right side, click it and there's the check boxes to get it going.
So far working perfectly!