Using the xubuntu desktop, on Ubuntu Raring updated from Quantal. MPlayer never really worked. No video, no audio, nothing. I really can't be any more helpful, so here's the log:

petey@home-pc:~$ mplayer "/home/petey/Downloads/Polar Bear Cafe
(480p)HorribleSubs]/[HorribleSubs] Polar Bear Cafe - 01 [480p].mkv"
MPlayer SVN-r35984-4.7 (C) 2000-2013 MPlayer Team

Playing /home/petey/Downloads/Polar Bear Cafe
(480p)[HorribleSubs]/[HorribleSubs] Polar Bear Cafe - 01 [480p].mkv.
libavformat version 55.0.100 (internal) libavformat file format
detected. [lavf] stream 0: video (h264), -vid 0 [lavf] stream 1: audio
(aac), -aid 0 [lavf] stream 2: subtitle (ass), -sid 0 VIDEO:  [H264] 
848x480  0bpp  23.810 fps    0.0 kbps ( 0.0 kbyte/s) Clip info: 
creation_time: 2012-04-05 21:36:10 Load subtitles in
/home/petey/Downloads/Polar Bear Cafe (480p)[HorribleSubs]/ Can't open
/dev/fb0: Permission denied [fbdev2] Can't open /dev/fb0: Permission
denied VO: [v4l2] No such file or directory vo_cvidix: No vidix driver
name provided, probing available ones (-v option for details)!
[cyberblade] Error occurred during pci scan: Operation not permitted
[mach64] Error occurred during pci scan: Operation not permitted [mga]
Error occurred during pci scan: Operation not permitted [mga] Error
occurred during pci scan: Operation not permitted [nvidia_vid] Error
occurred during pci scan: Operation not permitted [pm3] Error occurred
during pci scan: Operation not permitted [radeon] Error occurred
during pci scan: Operation not permitted [rage128] Error occurred
during pci scan: Operation not permitted [s3_vid] Error occurred
during pci scan: Operation not permitted [SiS] Error occurred during
pci scan: Operation not permitted [unichrome] Error occurred during
pci scan: Operation not permitted [VO_SUB_VIDIX] Couldn't find working
VIDIX driver.
==========================================================================
Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
libavcodec version 55.0.100 (internal) Selected video codec: [ffh264]
vfm: ffmpeg (FFmpeg H.264)
==========================================================================
==========================================================================
Opening audio decoder: [ffmpeg] FFmpeg/libavcodec audio decoders
AUDIO: 44100 Hz, 2 ch, floatle, 0.0 kbit/0.00% (ratio: 0->352800)
Selected audio codec: [ffaac] afm: ffmpeg (FFmpeg AAC (MPEG-2/MPEG-4
Audio))
==========================================================================
[AO OSS] audio_setup: Can't open audio device /dev/dsp: No such file
or directory DVB card number must be between 1 and 4 AO: [null]
44100Hz 2ch floatle (4 bytes per sample) Starting playback...
Movie-Aspect is 1.78:1 - prescaling to correct movie aspect. VO:
[null] 848x480 =    854x480 Planar YV12  A:   4.7 V:   4.7 A-V:  0.002
ct:  0.083   0/  0 22%  0%  0.5% 0 0              


MPlayer interrupted by signal 2 in module: sleep_timer A:   4.7 V:  
4.7 A-V:  0.001 ct:  0.083   0/  0 21%  0%  0.5% 0 0              

Exiting... (Quit)