For .avi and .mpeg files it is easy to install the plugins. but for .flv files
it is better to use either vlc player or mplayerI installed both and I prefer
VLC player
Both are in the repositories. they can be installed with sudo aptitude install
vlcsudo aptitude install mplayerAfter installing these you can choose whatever
movie player you want to use for playing a movie. I prefer VLC for .avi, .wmw
and .mpeg files, also.