Please describe the problem:
I just developed a small python script to transcode a video to theora/vorbis
with matroska as the muxer but the output lacks the video track.

I checked it changing to ogg muxer and it works so I guess it's a bug with the
matroska plugin.

After some checks I noticied that I was getting the error:
gstqueue.c(783): gst_queue_push_one (): /pipeline/voutq:
streaming stopped, reason not-negotiated

and executing gst-inspect I get:
carlos@aragorn:~$ gst-inspect-0.10 matroskamux
Factory Details:
  Long name:    Matroska muxer
  Class:        Codec/Muxer
  Description:  Muxes video/audio/subtitle streams into a matroska stream
  Author(s):    Ronald Bultje <rbultje@ronald.bitfreak.net>
  Rank:         none (0)

Plugin Details:
  Name:                 matroska
  Description:          Matroska stream handling
  Filename:             /usr/lib/gstreamer-0.10/libgstmatroska.so
  Version:              0.10.3
  License:              LGPL
  Source module:        gst-plugins-good
  Binary package:       GStreamer Good Plugins (Debian)
  Origin URL:           http://packages.qa.debian.org/gst-plugins-good0.10

GObject
 +----GstObject
       +----GstElement
             +----GstMatroskaMux

Pad Templates:
  SINK template: 'video_%d'
    Availability: On request
      Has request_new_pad() function: 0xb7a62696
    Capabilities:
      video/mpeg
            mpegversion: { 1, 2, 4 }
           systemstream: false
                  width: [ 16, 4096 ]
                 height: [ 16, 4096 ]
              framerate: [ 0/1, 2147483647/1 ]
      video/x-h264
                  width: [ 16, 4096 ]
                 height: [ 16, 4096 ]
              framerate: [ 0/1, 2147483647/1 ]
      video/x-divx
                  width: [ 16, 4096 ]
                 height: [ 16, 4096 ]
              framerate: [ 0/1, 2147483647/1 ]
      video/x-xvid
                  width: [ 16, 4096 ]
                 height: [ 16, 4096 ]
              framerate: [ 0/1, 2147483647/1 ]
      video/x-huffyuv
                  width: [ 16, 4096 ]
                 height: [ 16, 4096 ]
              framerate: [ 0/1, 2147483647/1 ]
      video/x-dv
                  width: [ 16, 4096 ]
                 height: [ 16, 4096 ]
              framerate: [ 0/1, 2147483647/1 ]
      video/x-h263
                  width: [ 16, 4096 ]
                 height: [ 16, 4096 ]
              framerate: [ 0/1, 2147483647/1 ]
      video/x-msmpeg
                  width: [ 16, 4096 ]
                 height: [ 16, 4096 ]
              framerate: [ 0/1, 2147483647/1 ]
      image/jpeg
                  width: [ 16, 4096 ]
                 height: [ 16, 4096 ]
              framerate: [ 0/1, 2147483647/1 ]
      video/x-raw-yuv
                 format: { YUY2, I420 }
                  width: [ 16, 4096 ]
                 height: [ 16, 4096 ]
              framerate: [ 0/1, 2147483647/1 ]

  SINK template: 'audio_%d'
    Availability: On request
      Has request_new_pad() function: 0xb7a62696
    Capabilities:
      audio/mpeg
            mpegversion: 1
                  layer: [ 1, 3 ]
               channels: [ 1, 8 ]
                   rate: [ 8000, 96000 ]
      audio/mpeg
            mpegversion: { 2, 4 }
               channels: [ 1, 8 ]
                   rate: [ 8000, 96000 ]
      audio/x-ac3
               channels: [ 1, 8 ]
                   rate: [ 8000, 96000 ]
      audio/x-vorbis
               channels: [ 1, 8 ]
                   rate: [ 8000, 96000 ]
      audio/x-raw-int
                  width: { 8, 16, 24 }
                  depth: { 8, 16, 24 }
             endianness: { 4321, 1234 }
                 signed: { true, false }
               channels: [ 1, 8 ]
                   rate: [ 8000, 96000 ]
      audio/x-tta
                  width: { 8, 16, 24 }
               channels: { 1, 2 }
                   rate: [ 8000, 96000 ]

  SINK template: 'subtitle_%d'
    Availability: On request
      Has request_new_pad() function: 0xb7a62696
    Capabilities:
      ANY

  SRC template: 'src'
    Availability: Always
    Capabilities:
      video/x-matroska


Element Flags:
  no flags set

Element Implementation:
  No loopfunc(), must be chain-based or not configured yet
  Has change_state() function: 0xb7a64b37
  Has custom save_thyself() function: gst_element_save_thyself
  Has custom restore_thyself() function: gst_element_restore_thyself

Element has no clocking capabilities.
Element has no indexing capabilities.

Pads:
  SRC: 'src'
    Implementation:
      Has custom eventfunc(): 0xb7a61707
    Pad Template: 'src'

Element Properties:
  name                : The name of the object
                        flags: readable, writable
                        String. Default: null Current: "matroskamux0"
  writing-app         : The name the application that creates the matroska file.
                       flags: readable, writable
                        String. Default: null Current: "GStreamer Matroska muxer"
  version             : This parameter determines what matroska features can be
used.
                        flags: readable, writable
                        Integer. Range: 1 - 2 Default: 1 Current: 1


from where you can see that video/x-theora is not there as one of the available
streams to store there.

Steps to reproduce:


Actual results:


Expected results:


Does this happen every time?
Yes

Other information:
I'm using Ubuntu Dapper with the package gstreamer0.10-plugins-good version
0.10.3 installed.