Fix Lyla showing up everywhere.

Previously XML data wasn't parsed in VideoDescriptor.__init__, leading
to the defaults being used for video settings.

common/lib/xmodule/xmodule/tests/test_video_module.py

 # -*- coding: utf-8 -*-
 import unittest
 
+from xmodule.modulestore import Location
 from xmodule.video_module import VideoDescriptor
 from .test_import import DummySystem
 
@@ -10,6 +11,33 @@ class VideoDescriptorImportTestCase(unittest.TestCase):
     Make sure that VideoDescriptor can import an old XML-based video correctly.
     """
 
+    def test_constructor(self):
+        sample_xml = '''
+            <video display_name="Test Video"
+                   youtube="1.0:p2Q6BrNhdh8,0.75:izygArpw-Qo,1.25:1EeWXzPdhSA,1.5:rABDYkeK0x8"
+                   show_captions="false"
+                   from="00:00:01"
+                   to="00:01:00">
+              <source src="http://www.example.com/source.mp4"/>
+              <track src="http://www.example.com/track"/>
+            </video>
+        '''
+        location = Location(["i4x", "edX", "video", "default",
+                             "SampleProblem1"])
+        model_data = {'data': sample_xml,
+                      'location': location}
+        system = DummySystem(load_error_modules=True)
+        descriptor = VideoDescriptor(system, model_data)
+        self.assertEquals(descriptor.youtube_id_0_75, 'izygArpw-Qo')
+        self.assertEquals(descriptor.youtube_id_1_0, 'p2Q6BrNhdh8')
+        self.assertEquals(descriptor.youtube_id_1_25, '1EeWXzPdhSA')
+        self.assertEquals(descriptor.youtube_id_1_5, 'rABDYkeK0x8')
+        self.assertEquals(descriptor.show_captions, False)
+        self.assertEquals(descriptor.start_time, 1.0)
+        self.assertEquals(descriptor.end_time, 60)
+        self.assertEquals(descriptor.track, 'http://www.example.com/track')
+        self.assertEquals(descriptor.source, 'http://www.example.com/source.mp4')
+
     def test_from_xml(self):
         module_system = DummySystem(load_error_modules=True)
         xml_data = '''

common/lib/xmodule/xmodule/video_module.py

@@ -88,6 +88,13 @@ class VideoDescriptor(VideoFields,
     module_class = VideoModule
     template_dir_name = "video"
 
+    def __init__(self, *args, **kwargs):
+        super(VideoDescriptor, self).__init__(*args, **kwargs)
+        # If we don't have a `youtube_id_1_0`, this is an XML course
+        # and we parse out the fields.
+        if self.data and 'youtube_id_1_0' not in self._model_data:
+            _parse_video_xml(self, self.data)
+
     @property
     def non_editable_metadata_fields(self):
         non_editable_fields = super(MetadataOnlyEditingDescriptor, self).non_editable_metadata_fields
@@ -108,47 +115,54 @@ class VideoDescriptor(VideoFields,
             url identifiers
         """
         video = super(VideoDescriptor, cls).from_xml(xml_data, system, org, course)
-        xml = etree.fromstring(xml_data)
-
-        display_name = xml.get('display_name')
-        if display_name:
-            video.display_name = display_name
-
-        youtube = xml.get('youtube')
-        if youtube:
-            speeds = _parse_youtube(youtube)
-            if speeds['0.75']:
-                video.youtube_id_0_75 = speeds['0.75']
-            if speeds['1.00']:
-                video.youtube_id_1_0 = speeds['1.00']
-            if speeds['1.25']:
-                video.youtube_id_1_25 = speeds['1.25']
-            if speeds['1.50']:
-                video.youtube_id_1_5 = speeds['1.50']
-
-        show_captions = xml.get('show_captions')
-        if show_captions:
-            video.show_captions = json.loads(show_captions)
-
-        source = _get_first_external(xml, 'source')
-        if source:
-            video.source = source
-
-        track = _get_first_external(xml, 'track')
-        if track:
-            video.track = track
-
-        start_time = _parse_time(xml.get('from'))
-        if start_time:
-            video.start_time = start_time
-
-        end_time = _parse_time(xml.get('to'))
-        if end_time:
-            video.end_time = end_time
-
+        _parse_video_xml(video, xml_data)
         return video
 
 
+def _parse_video_xml(video, xml_data):
+    """
+    Parse video fields out of xml_data. The fields are set if they are
+    present in the XML.
+    """
+    xml = etree.fromstring(xml_data)
+
+    display_name = xml.get('display_name')
+    if display_name:
+        video.display_name = display_name
+
+    youtube = xml.get('youtube')
+    if youtube:
+        speeds = _parse_youtube(youtube)
+        if speeds['0.75']:
+            video.youtube_id_0_75 = speeds['0.75']
+        if speeds['1.00']:
+            video.youtube_id_1_0 = speeds['1.00']
+        if speeds['1.25']:
+            video.youtube_id_1_25 = speeds['1.25']
+        if speeds['1.50']:
+            video.youtube_id_1_5 = speeds['1.50']
+
+    show_captions = xml.get('show_captions')
+    if show_captions:
+        video.show_captions = json.loads(show_captions)
+
+    source = _get_first_external(xml, 'source')
+    if source:
+        video.source = source
+
+    track = _get_first_external(xml, 'track')
+    if track:
+        video.track = track
+
+    start_time = _parse_time(xml.get('from'))
+    if start_time:
+        video.start_time = start_time
+
+    end_time = _parse_time(xml.get('to'))
+    if end_time:
+        video.end_time = end_time
+
+
 def _get_first_external(xmltree, tag):
     """
     Returns the src attribute of the nested `tag` in `xmltree`, if it