Killing the app from the terminal renders the video source unusable

killing the app from the terminal renders the video source unusable requiring a re-plugging the usb for it to work again.

1ste run, Video output visible:

levi@ubanix ~/p/e/f/build> snap-photobooth 130
[_LOG_LEVEL_INFO 01:35:45.546613] Application.vala:155: Snap version: 0.1
[_LOG_LEVEL_INFO 01:35:45.546662] Application.vala:157: Kernel version: 3.13.0-48-generic
[_LOG_LEVEL_DEBUG 01:35:45.547490] Settings.vala:158: Loading settings from schema 'org.pantheon.snap.settings'
[_LOG_LEVEL_WARN 01:35:45.553395] Couldn't connect to accessibility bus: Failed to connect to socket /tmp/dbus-ku8eqiW9WB: Connection refused
[_LOG_LEVEL_DEBUG 01:35:45.599417] [Gtk] Connecting to session manager
[_LOG_LEVEL_DEBUG 01:35:45.601973] SnapWindow.vala:214: camera found: video0
[_LOG_LEVEL_FATAL 01:35:45.604157] [GLib-GObject] g_value_set_pointer: assertion 'G_VALUE_HOLDS_POINTER (value)' failed
[_LOG_LEVEL_FATAL 01:35:45.604196] Snap will not function properly.
libv4l2: error turning on stream: Invalid argument
[_LOG_LEVEL_DEBUG 01:35:45.667859] Camera.vala:95: Getting the video-size failed: Internal data flow error.
[_LOG_LEVEL_DEBUG 01:35:46.799964] Camera.vala:107: mode changed
levi@ubanix ~/p/e/f/build> snap-photobooth
[_LOG_LEVEL_INFO 01:46:01.756180] Application.vala:155: Snap version: 0.1
[_LOG_LEVEL_INFO 01:46:01.756237] Application.vala:157: Kernel version: 3.13.0-48-generic
[_LOG_LEVEL_DEBUG 01:46:01.757076] Settings.vala:158: Loading settings from schema 'org.pantheon.snap.settings'
[_LOG_LEVEL_WARN 01:46:01.760188] Couldn't connect to accessibility bus: Failed to connect to socket /tmp/dbus-ku8eqiW9WB: Connection refused
[_LOG_LEVEL_DEBUG 01:46:01.790826] [Gtk] Connecting to session manager
[_LOG_LEVEL_DEBUG 01:46:01.793443] SnapWindow.vala:214: camera found: video0
[_LOG_LEVEL_FATAL 01:46:01.795553] [GLib-GObject] g_value_set_pointer: assertion 'G_VALUE_HOLDS_POINTER (value)' failed
[_LOG_LEVEL_FATAL 01:46:01.795586] Snap will not function properly.
[_LOG_LEVEL_DEBUG 01:46:04.198827] Camera.vala:107: mode changed
[_LOG_LEVEL_DEBUG 01:46:07.181214] Camera.vala:129: Recording...
[_LOG_LEVEL_DEBUG 01:46:07.181901] Camera.vala:140: /home/levi/Pictures/Webcam/2015-04-0101:46:07.jpg
^C

Second run, no video:

levi@ubanix ~/p/e/f/build> snap-photobooth 130
[_LOG_LEVEL_INFO 01:58:41.692612] Application.vala:155: Snap version: 0.1
[_LOG_LEVEL_INFO 01:58:41.692668] Application.vala:157: Kernel version: 3.13.0-48-generic
[_LOG_LEVEL_DEBUG 01:58:41.693517] Settings.vala:158: Loading settings from schema 'org.pantheon.snap.settings'
[_LOG_LEVEL_WARN 01:58:41.696664] Couldn't connect to accessibility bus: Failed to connect to socket /tmp/dbus-ku8eqiW9WB: Connection refused
[_LOG_LEVEL_DEBUG 01:58:41.729102] [Gtk] Connecting to session manager
[_LOG_LEVEL_DEBUG 01:58:41.731652] SnapWindow.vala:214: camera found: video0
[_LOG_LEVEL_FATAL 01:58:41.733755] [GLib-GObject] g_value_set_pointer: assertion 'G_VALUE_HOLDS_POINTER (value)' failed
[_LOG_LEVEL_FATAL 01:58:41.733785] Snap will not function properly.
libv4l2: error turning on stream: Invalid argument
[_LOG_LEVEL_DEBUG 01:58:41.799525] Camera.vala:95: Getting the video-size failed: Internal data flow error.
[_LOG_LEVEL_DEBUG 01:58:42.951176] Camera.vala:107: mode changed
[_LOG_LEVEL_DEBUG 01:58:45.852875] Camera.vala:129: Recording...
[_LOG_LEVEL_DEBUG 01:58:45.853529] Camera.vala:140: /home/levi/Pictures/Webcam/2015-04-0101:58:45.jpg
^C

The "Recording..." phase never stored an image.

Closing the app using the window controls results in a clean exit and the video feed continue to work in subsequent runs.
For testing it would be useful to be able to kill the app straight from the terminal.