I used the answer to this question to change the default software for opening video files to VLC player on Ubuntu 12.04. The settings say that this is now the default player and yet whenever I play the files they are still opening with Movie Player. Is there anything I can do to fix this or must I uninstall Movie Player ????
You can right click on a file, go to the last entry (Properties) and select in the new window the 'Open with' tab.
There you see the standard-application, the recommended app and other apps for opening this file.
In the list of other applications, you can select which application to use for opening the movie. (VLC media player)
Now the file should be opened by VLC.
A more global solution.
for the video types you need jus replace the current entry for exmaple video/3gpp=totem.desktop to video/3gpp=vlc.desktop.