Resource busy or not available. xvimagesink.c

[yoursunny]

I install this on a Ubuntu 12.04 box. When I run ndnvideo/videostreaming/play.py /ndn/ucla.edu/apps/video, no video appears, and console reports this error repeatedly.

Error: Resource busy or not available. xvimagesink.c(1443): gst_xvimagesink_get_xv_support (): /GstPipeline:pipeline0/GstXvImageSink:xvimagesink0:
No port available

Packages I have: gstreamer-tools gstreamer0.10-plugins-ugly python-gst0.10-dev

I confirm import pygst works.
gst-launch only works on the first command:

sunny@sunnyp:~$ gst-launch videotestsrc ! ximagesink
Setting pipeline to PAUSED ...
Pipeline is PREROLLING ...
Pipeline is PREROLLED ...
Setting pipeline to PLAYING ...
New clock: GstSystemClock
ERROR: from element /GstPipeline:pipeline0/GstXImageSink:ximagesink0: Output window was closed
Additional debug info:
ximagesink.c(1119): gst_ximagesink_handle_xevents (): /GstPipeline:pipeline0/GstXImageSink:ximagesink0
Execution ended after 3178341661 ns.
Setting pipeline to PAUSED ...
Setting pipeline to READY ...
Setting pipeline to NULL ...
Freeing pipeline ...
sunny@sunnyp:~$ gst-launch v4l2src ! ximagesink
Setting pipeline to PAUSED ...
ERROR: Pipeline doesn't want to pause.
ERROR: from element /GstPipeline:pipeline0/GstV4l2Src:v4l2src0: Cannot identify device '/dev/video0'.
Additional debug info:
v4l2_calls.c(493): gst_v4l2_open (): /GstPipeline:pipeline0/GstV4l2Src:v4l2src0:
system error: No such file or directory
Setting pipeline to NULL ...
Freeing pipeline ...
sunny@sunnyp:~$ gst-launch v4l2src ! x264enc ! ffdec_h264 ! ximagesink
Setting pipeline to PAUSED ...
ERROR: Pipeline doesn't want to pause.
ERROR: from element /GstPipeline:pipeline0/GstV4l2Src:v4l2src0: Cannot identify device '/dev/video0'.
Additional debug info:
v4l2_calls.c(493): gst_v4l2_open (): /GstPipeline:pipeline0/GstV4l2Src:v4l2src0:
system error: No such file or directory
Setting pipeline to NULL ...
Freeing pipeline ...