Plugin (compiled for x64 Linux from current git) supports these MIME types, taken from pref pane:
application/mpeg4-iod (MPEG-4 video: mp4,mpg4),
application/mpeg4-muxcodetable (MPEG-4 video: mp4,mpg4),
application/ogg (Ogg stream: ogg),
application/vnd.rn-realmedia (Real Media File: rm),
application/x-google-vlc-plugin (Google VLC plug-in),
application/x-matroska (Matroska video: mkv),
application/x-mplayer2 (Windows Media),
application/x-ogg (Ogg stream: ogg),
application/x-vlc-plugin (VLC plug-in),
application/xspf+xml (Playlist xspf: xspf),
audio/3gpp (3GPP audio: 3gp,3gpp),
audio/3gpp2 (3GPP2 audio: 3g2,3gpp2),
audio/amr (AMR audio: amr),
audio/flac (FLAC audio: flac),
audio/m4a (MPEG-4 audio: m4a),
audio/mp4 (MPEG-4 audio: aac,mp4,mpg4),
audio/mpeg (MPEG audio: mp2,mp3,mpga,mpega),
audio/ogg (Ogg audio: oga),
audio/ogg;codecs=opus (Opus audio: opus),
audio/wav (WAV audio: wav),
audio/webm (WebM audio: webm),
audio/x-flac (FLAC audio: flac),
audio/x-m4a (MPEG-4 audio: m4a),
audio/x-matroska (Matroska audio: mka),
audio/x-mpeg (MPEG audio: mp2,mp3,mpga,mpega),
audio/x-mpegurl (MPEG audio: m3u),
audio/x-ms-wma (Windows Media Audio: wma),
audio/x-realaudio (Real Media Audio: ra),
audio/x-wav (WAV audio: wav),
video/3gpp (3GPP video: 3gp,3gpp),
video/3gpp2 (3GPP2 video: 3g2,3gpp2),
video/divx (DivX video: divx),
video/flv (FLV video: flv),
video/mp4 (MPEG-4 video: mp4,mpg4),
video/mpeg (MPEG video: mpg,mpeg,mpe),
video/mpeg-system (MPEG video: mpg,mpeg,mpe,vob),
video/ogg (Ogg video: ogv),
video/quicktime (QuickTime video: mov,qt),
video/webm (WebM video: webm),
video/x-flv (FLV video: flv),
video/x-m4v (MPEG-4 video: m4v),
video/x-matroska (Matroska video: mkv),
video/x-mpeg (MPEG video: mpg,mpeg,mpe),
video/x-mpeg-system (MPEG video: mpg,mpeg,mpe,vob),
video/x-ms-asf (Windows Media Video: asf,asx),
video/x-ms-asf-plugin (Windows Media Video: asf,asx),
video/x-ms-wmv (Windows Media: wmv),
video/x-ms-wvx (Windows Media Video: wvx),
video/x-msvideo (AVI video: avi)
NB: Output sorted to enhance readability.