I use mplayer to view my videos. However, in 12.04, after installing mplayer, I do not see open with option in preference dialog. Could you please tell me how to add mplayer to the list.
I am pasting screenshot of my menus. Please let me know If I am missing any thing.
Note: In second image, video option contains single Movie player entry.
I had a similar problem with gnome. I used mimeopen to solve it, but the command was a little different :
With this I could associate mp4 files with the mplayer command again.
Without "-d" it would use totem without asking.
For the reference, I found that mimeopen helps to set via command line.
To set the file type to open with particular program use mimeopen as follows.
Upon asking, choose the program if present in the menu. As mplayer was not available, I chose #2.
Now, If I open any .avi files via GUI, it opens, by default, with mplayer.