Here's a copy of my mplayerplug-in.types file
video/quicktime:mov:Quicktime;
video/x-quicktime:mov:Quicktime;
video/quicktime:mp4:Quicktime;
video/quicktime:sdp:Quicktime - Session Description Protocol;
application/x-quicktimeplayer:mov:Quicktime;
video/x-msvideo:avi:AVI;
video/msvideo:avi:AVI;
video/mpeg:mpg,mpeg:MPEG;
video/mp4:mp4:MPEG Video;
video/x-mpeg:mpg,mpeg:MPEG;
video/x-mpeg2:mpv2,mp2ve:MPEG2;
audio/x-pn-realaudio:ram:RealAudio;
audio/x-pn-realaudio-plugin:rpm:RealAudio;
audio/x-realaudio:ra:RealAudio;
video/fli:fli,flc:FLI animation;
video/x-fli:fli,flc:FLI animation;
video/x-ms-asf-plugin:asf,asx:Windows Media;
video/dl:dl
L animation;
video/x-dl:dl
L animation;
video/sgi-movie:movie,moci,mv:SGI animation;
video/x-sgi-movie:movie,moci,mv:SGI animation;
video/anim:iff,anim5,anim3,anim7:IFF animation;
video/x-anim:iff,anim5,anim3,anim7:IFF animation;
application/x-ogg
gg:Ogg Vorbis Media;
audio/ogg
gg:Ogg Vorbis Audio;
application/ogg
gg:Ogg Vorbis;
application/x-mplayer2:wmv:WMV;
video/x-ms-wm:asf:MSNBCPlayer;
video/x-ms-asf:asf,asx:Windows Media;
video/x-ms-wmv:wmv:Windows Media;
video/x-ms-wvx:wvx:Windows Media;
audio/x-ms-wax:wax:Windows Media;
audio/x-ms-wma:wma:Windows Media;
application/x-drm-v2:asx:Windows Media;
audio/wav:wav:Microsoft wave file;
audio/x-wav:wav:Microsoft wave file;
application/smil:smil:SMIL;
application/x-oleobject:asx:WMP;
Hope it helps