Okay so I had the whole problem where I would try to stream Videos or Music on my Xbox 360 from my Windows 8 PC and my computer would never show up in the list of streamable devices and I looked online and found TVersity downloaded a free version of it and it didn't work.. So I kept looking and I played around with my PC on the Control Panel and figured out that if you do these steps in order it resets your media stream on your PC.
**YOU MAY NEED ADMINISTRATOR PRIVELAGES FOR THIS FIX**
1) Go to Control Panel
2) Click on Network and Internet
3) Click on Network and Sharing Center
4) In the top left off to the side you should see "Change advanced sharing settings" click that
5) Now under the "All Networks" Tab you should see "Public folder sharing" I'm not 100% this is important but turn it off
6) After you turn "Public folder sharing" off click save changes and re-open "Change advanced sharing settings"
7) This time go to "Media streaming" and click choose "Choose media streaming options"
8) When you open that click block all and click "Ok"
9) Now you should be back in the "Change advanced sharing settings" menu now turn "Public folder sharing" back on
10) Now click "Choose media streaming options" and it should have a box asking if you want to enable media streaming click it
11) Finally click "Save changes" and check and see if your Xbox 360 can find your computer
What this fix does is reset your media streaming service on your PC, there may be a simpler way to do this that I'm not aware of but this is quick and works every time for me.
I hope this fix works for everyone that tries it :)