If you're using ivtv you need to configure the VIDEO_GROUPS section in local_conf.py. An example for North America is:
VIDEO_GROUPS = [
    VideoGroup(vdev='/dev/video0',
               adev=None,
               input_type='tuner',
               input_num=4,
               tuner_norm='NTSC',
               tuner_chanlist='us-cable',
               desc='Regular cable',
               group_type='ivtv',
               recordable=True),
               ]
Make sure you take note of the input_num part. That is the input number of the tuner on my ivtv card - svideo / composite are different numbers.
The mplayer TV plugin looks at this information and decides whether or not to use tv:// (which doesn't work for ivtv) or to setup the ivtv device itself.
You'll also want to activate the ivtv recording plugin.
plugin.remove('tv.generic_record')
plugin_record = plugin.activate('tv.ivtv_record')
TV_IVTV_OPTIONS = {
     'input'         : 6,
     'resolution'    : '720x576',
     'aspect'        : 2,
     'audio_bitmask' : 0xE9,
     'bframes'       : 3,
     'bitrate_mode'  : 0,
     'bitrate'       : 8000000,
     'bitrate_peak'  : 9600000,
     'dnr_mode'      : 3,
     'dnr_spatial'   : 0,
     'dnr_temporal'  : 0,
     'dnr_type'      : 0,
     'framerate'     : 0,
     'framespergop'  : 12,
     'gop_closure'   : 1,
     'pulldown'      : 0,
     'stream_type'   : 14,
}
For a description of the dnr_* options see: ![[WWW]](modern/img/moin-www.png) http://ivtvdriver.org/trac/file/ivtv/trunk/doc/video-quality.txt
 http://ivtvdriver.org/trac/file/ivtv/trunk/doc/video-quality.txt