As bugs go, I think the initial bug is fixed.

I now get this when arista queues my DVD to PSP-Low transcoding job:

displague@split:~$ arista-gtk 
libdvdread: Using libdvdcss version 1.2.10 for DVD access

libdvdread: Attempting to retrieve all CSS keys
libdvdread: This can take a _long_ time, please be patient

libdvdread: Get key for /VIDEO_TS/VTS_01_0.VOB at 0x000001aa
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_01_1.VOB at 0x00006daa
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_02_0.VOB at 0x0012f837
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_02_1.VOB at 0x0012f870
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_03_0.VOB at 0x0013755e
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_03_1.VOB at 0x00137597
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_04_0.VOB at 0x00138259
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_04_1.VOB at 0x00138292
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_05_0.VOB at 0x00138f6a
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_05_1.VOB at 0x00138fa3
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_06_0.VOB at 0x00139604
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_06_1.VOB at 0x0013963d
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_07_0.VOB at 0x0013a495
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_07_1.VOB at 0x0013a4ce
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_08_0.VOB at 0x0013ace7
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_08_1.VOB at 0x0013ad20
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_09_0.VOB at 0x0013b67b
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_09_1.VOB at 0x0013b6b4
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_10_0.VOB at 0x0013c53a
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_10_1.VOB at 0x0013c573
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_11_0.VOB at 0x0013c980
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_11_1.VOB at 0x0013c9b9
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_12_0.VOB at 0x0013d7a1
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_12_1.VOB at 0x0013d7da
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_13_0.VOB at 0x0013e464
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_13_1.VOB at 0x0013e49d
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_14_0.VOB at 0x0013ef96
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_14_1.VOB at 0x0013efcf
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_15_0.VOB at 0x0013f838
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_15_1.VOB at 0x0013f871
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_16_0.VOB at 0x00140385
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_16_1.VOB at 0x001403be
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_17_0.VOB at 0x00140d4b
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_17_1.VOB at 0x00140d84
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_18_0.VOB at 0x0014b5a6
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_18_1.VOB at 0x0014b5df
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_19_0.VOB at 0x00152f9a
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_19_1.VOB at 0x00152fd3
libdvdread: Elapsed time 0
libdvdread: Found 19 VTS's
libdvdread: Elapsed time 0

(arista-gtk:3356): GStreamer-CRITICAL **: 
Trying to dispose element queue0, but it is in PLAYING instead of the NULL state.
You need to explicitly set elements to the NULL state before
dropping the final reference, to allow them to clean up.
This problem may also be caused by a refcounting bug in the
application or some element.

sys:1: Warning: g_object_ref: assertion `object->ref_count > 0' failed

(arista-gtk:3356): GStreamer-CRITICAL **: gst_object_unref: assertion `((GObject *) object)->ref_count > 0' failed

GThread-ERROR **: file /build/buildd/glib2.0-2.25.9/gthread/gthread-posix.c: line 171 (g_mutex_free_posix_impl): error 'Device or resource busy' during 'pthread_mutex_destroy ((pthread_mutex_t *) mutex)'
aborting...
Trace/breakpoint trap