I have several movie player in my ubuntu include Mplayer,Realplayer,gstreamer (the default movie player).Everytime I click on a vedio file,gstreamer starts up with an error on codecs.So I delete gstreamer by following command in terminal(It cannot be erased from Application–>Add/Remove…)

sudo apt-get autoremove totem-gstreamer

I want to use Mplayer as my default movie player,but other movie player starts up when I click video files.And following is what I did with it.
Right click on a video file,select Properties and navigate to Open With tab,tick Mplayer.If it’s a .mp4 file,next time you open a .mp4 file,Mplayer starts up.If you remove all other applications in the box only Mplayer left,all video files starts up by mplayer for default.

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To set default player for firefox

Type about:config in address bar,click on “I promise,I’ll be careful” when prompt.Search “network.protocol-handler.app.rtsp”in Filter and change it’s value to “mplayer”.If it’s not exist,right click on blank and select  New->String

to create.Enter “network.protocol-handler.app.rtsp”,”mplayer” in turn.

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