$ mplayer -vc theora -ac vorbis http://video.debconf.org:8000/Salon_del_mar.ogv
MPlayer dev-SVN-r26940
CPU: Intel Celeron Covington/Pentium II Deschutes,Tonga/Pentium II Xeon (Family: 6, Model: 5, Stepping: 2)
CPUflags:  MMX: 1 MMX2: 0 3DNow: 0 3DNow2: 0 SSE: 0 SSE2: 0
Compiled with runtime CPU detection.
Can't open joystick device /dev/input/js0: No such file or directory
Can't init input joystick

Playing http://video.debconf.org:8000/Salon_del_mar.ogv.
Resolving video.debconf.org for AF_INET6...
Couldn't resolve name for AF_INET6: video.debconf.org
Resolving video.debconf.org for AF_INET...
Connecting to server video.debconf.org[137.82.84.44]: 8000...
Name   : no name
Public : no
Cache size set to 4096 KBytes
Cache fill: 19.92% (835584 bytes)
Ogg stream 0 is of an unknown type
[Ogg] stream 1: video (Theora v3.2.1), -vid 0
[Ogg] stream 2: audio (Vorbis), -aid 0
Ogg file format detected.
VIDEO:  [theo]  320x240  24bpp  25.000 fps    0.0 kbps ( 0.0 kbyte/s)
[VO_XV] Using Xv Adaptor #0 (NV Video Blitter)
==========================================================================
Forced video codec: theora
Opening video decoder: [theora] Theora/VP3
VDec: vo config request - 320 x 240 (preferred colorspace: Planar YV12)
VDec: using Planar YV12 as output csp (no 0)
Movie-Aspect is 1.33:1 - prescaling to correct movie aspect.
VO: [xv] 320x240 => 320x240 Planar YV12
Selected video codec: [theora] vfm: theora (Theora (free, reworked VP3))
==========================================================================
==========================================================================
Forced audio codec: vorbis
Opening audio decoder: [libvorbis] Ogg/Vorbis audio decoder
AUDIO: 48000 Hz, 2 ch, s16le, 64.0 kbit/4.17% (ratio: 8000->192000)
Selected audio codec: [vorbis] afm: libvorbis (OggVorbis Audio Decoder)
==========================================================================
AO: [alsa] 48000Hz 2ch s16le (2 bytes per sample)
Starting playback...
Ogg : bad packet in stream 1
Ogg : bad packet in stream 2
A:1930.9 V:1930.9 A-V:  0.008 ct: -0.255 5031/5031 24%  3%  6.9% 44 0 19%