$ mplayer /dev/video0 
MPlayer 2:1.0~rc1-0ubuntu9.1 (C) 2000-2006 MPlayer Team
CPU: AMD Sempron(tm) Processor 3000+ (Family: 15, Model: 44, Stepping: 2)
CPUflags:  MMX: 1 MMX2: 1 3DNow: 1 3DNow2: 1 SSE: 1 SSE2: 1
Compiled with runtime CPU detection.
Can't open joystick device /dev/input/js0: No such file or directory
Can't init input joystick
mplayer: could not connect to socket
mplayer: No such file or directory
Failed to open LIRC support. You will not be able to use your remote control.

Playing /dev/video0.
Cannot seek backward in linear streams!
Seek failed
Cannot seek backward in linear streams!
Seek failed
Cannot seek backward in linear streams!
Seek failed
Cannot seek backward in linear streams!
Seek failed
Cannot seek backward in linear streams!
Seek failed
Cannot seek backward in linear streams!
Seek failed
Cannot seek backward in linear streams!
Seek failed
Cannot seek backward in linear streams!
Seek failed
Cannot seek backward in linear streams!
Seek failed
Cannot seek backward in linear streams!
Seek failed
Cannot seek backward in linear streams!
Seek failed
Cannot seek backward in linear streams!
Seek failed
Cannot seek backward in linear streams!
Seek failed
MPEG-PS file format detected.
VIDEO:  MPEG2  720x480  (aspect 2)  29.970 fps  8000.0 kbps (1000.0 kbyte/s)
open: No such file or directory
[MGA] Couldn't open: /dev/mga_vid
open: No such file or directory
[MGA] Couldn't open: /dev/mga_vid
[VO_TDFXFB] Can't open /dev/fb0: No such file or directory.
[VO_3DFX] Unable to open /dev/3dfx.
==========================================================================
Opening video decoder: [mpegpes] MPEG 1/2 Video passthrough
VDec: vo config request - 720 x 480 (preferred colorspace: Mpeg PES)
Could not find matching colorspace - retrying with -vf scale...
Opening video filter: [scale]
The selected video_out device is incompatible with this codec.
Try adding the scale filter, e.g. -vf spp,scale instead of -vf spp.
VDecoder init failed :(
Opening video decoder: [libmpeg2] MPEG 1/2 Video decoder libmpeg2-v0.4.0b
Selected video codec: [mpeg12] vfm: libmpeg2 (MPEG-1 or 2 (libmpeg2))
==========================================================================
==========================================================================
Forced audio codec: mad
Opening audio decoder: [libmad] libmad mpeg audio decoder
AUDIO: 48000 Hz, 2 ch, s16le, 224.0 kbit/14.58% (ratio: 28000->192000)
Selected audio codec: [mad] afm: libmad (libMAD MPEG layer 1-2-3)
==========================================================================
AO: [alsa] 48000Hz 2ch s16le (2 bytes per sample)
Starting playback...
VDec: vo config request - 720 x 480 (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] 720x480 => 720x540 Planar YV12 
A:   1.8 V:   1.9 A-V: -0.079 ct: -0.120  37/ 37 23%  1% 40.9% 0 0