debugging gstreamer

$ lldb gst-launch-1.0 uridecodebin uri=http://docs.gstreamer.com/media/sintel_trailer-480p.webm ! videoconvert ! autovideosink
(lldb) target create "gst-launch-1.0"
Current executable set to 'gst-launch-1.0' (x86_64).
(lldb) settings set -- target.run-args  "uridecodebin" "uri=http://docs.gstreamer.com/media/sintel_trailer-480p.webm" "!" "videoconvert" "!" "autovideosink"
(lldb) run
Process 6926 launched: '/opt/local/bin/gst-launch-1.0' (x86_64)
Setting pipeline to PAUSED ...
Pipeline is PREROLLING ...
Got context from element 'autovideosink0-actual-sink-glimage': gst.gl.GLDisplay=context, gst.gl.GLDisplay=(GstGLDisplay)"\(GstGLDisplay\)\ gldisplay0";
Process 6926 stopped
* thread #13: tid = 0x34368, 0x000000010357305b libX11.6.dylib`XQueryExtension + 33, stop reason = EXC_BAD_ACCESS (code=1, address=0x968)
    frame #0: 0x000000010357305b libX11.6.dylib`XQueryExtension + 33
libX11.6.dylib`XQueryExtension + 33:
-> 0x10357305b:  movq   0x968(%rbx), %rax
   0x103573062:  testq  %rax, %rax
   0x103573065:  je     0x10357306c               ; XQueryExtension + 50
   0x103573067:  movq   %rbx, %rdi
(lldb)