Add acceptance test for XML-only video content.

Since we've had issues with the default video being incorrectly shown,
this creates an XML-only video and ensures that the correct
(non-default) Youtube ID is sent to the client.

cms/djangoapps/contentstore/features/video.feature

@@ -47,3 +47,7 @@ Feature: Video Component
     Given I have created a Video Alpha component
     And I have set "show captions" to True
     Then when I view the videoalpha it does show the captions
+
+  Scenario: Video data is shown correctly
+    Given I have created a video with only XML data
+    Then the correct Youtube video is shown

cms/djangoapps/contentstore/features/video.py

@@ -2,6 +2,9 @@
 
 from lettuce import world, step
 from terrain.steps import reload_the_page
+from xmodule.modulestore import Location
+from contentstore.utils import get_modulestore
+
 
 ############### ACTIONS ####################
 
@@ -44,3 +47,39 @@ def videoalpha_name_persisted(step):
     reload_the_page(step)
     world.edit_component()
     world.verify_setting_entry(world.get_setting_entry('Display Name'), 'Display Name', '3.4', True)
+
+
+@step('I have created a video with only XML data')
+def xml_only_video(step):
+    # Create a new video *without* metadata. This requires a certain
+    # amount of rummaging to make sure all the correct data is present
+    step.given('I have clicked the new unit button')
+
+    # Wait for the new unit to be created and to load the page
+    world.wait(1)
+
+    location = world.scenario_dict['COURSE'].location
+    store = get_modulestore(location)
+
+    parent_location = store.get_items(Location(category='vertical', revision='draft'))[0].location
+
+    youtube_id = 'ABCDEFG'
+    world.scenario_dict['YOUTUBE_ID'] = youtube_id
+
+    # Create a new Video component, but ensure that it doesn't have
+    # metadata. This allows us to test that we are correctly parsing
+    # out XML
+    video = world.ItemFactory.create(
+        parent_location=parent_location,
+        category='video',
+        data='<video youtube="1.00:%s"></video>' % youtube_id
+    )
+
+    # Refresh to see the new video
+    reload_the_page(step)
+
+
+@step('The correct Youtube video is shown')
+def the_youtube_video_is_shown(_step):
+    ele = world.css_find('.video').first
+    assert ele['data-youtube-id-1-0'] == world.scenario_dict['YOUTUBE_ID']