How to change default media player setting in Mountain Lion

Question

I right click on the desired media player, then I click on "get info" and another pop up appears,
but there is no "open with" selection!  See pic below:
I open the application folder in the Finder window, I highlight the desired media player, I go to the top and
click on File and in the drop down menu, the "open with" is grayed out.  Why?
How do I change the default media player setting or better yet, where do I find what is the default player?  Help Please!

Answer 1

CheeMiss8
you need to find the file you are trying to have open with a specific application.
for example, I'm going to use an MP4 file titled cat_adventure video.
here it is in finder
I right click (secondary click) it in finder, and then hold down the option key on my keyboard.
the Open With dialogue should change to "Always Open With" and then you choose your application from the pull out menu when you hover that.
You can make it so all MP4 or whichever file you are using (AVI, MKV, etc) to open with a specific app by right clicking the file choosing get info
The difference here is I'm not selecting the application but a file with the extension of the video format I always want to be opened with a specific application
once in the get info menu I can then select to have the video always open with a certain app.
1.click the open with accordion menu arrow if it is pointing to the left. it should be pointing down.
2.select the application you want to always be associated with that file format
3.select Change All to have that file format always be opened with that Application.
Where this isn't working for you is because you are doing this to the Application itself. you don't do it like that. You need to find the type of file you are trying to open with itunes and then go through these steps.
selecting the application (itunes) instead of the file (mp4, avi, mkv, flv) will not allow you to set what the file format lets you use to play your video.
having said that, itunes is very limited in what it can and can't play. Mainly .mov and mp4's (apples proprietary extensions)