Merge pull request #583 from MITx/rocha/master

[#35065403] Lets video player work if subtitles cannot be loaded

common/lib/xmodule/xmodule/js/src/video/display/video_caption.coffee

 class @VideoCaption extends Subview
+  initialize: ->
+    @loaded = false  
+
   bind: ->
     $(window).bind('resize', @resize)
     @$('.hide-subtitles').click @toggle
@@ -24,6 +27,8 @@ class @VideoCaption extends Subview
       @captions = captions.text
       @start = captions.start
 
+      @loaded = true
+
       if onTouchBasedDevice()
         $('.subtitles li').html "Caption will be displayed when you start playing the video."
       else
@@ -47,6 +52,7 @@ class @VideoCaption extends Subview
     @rendered = true
 
   search: (time) ->
+    if @loaded
       min = 0
       max = @start.length - 1
 
@@ -56,17 +62,19 @@ class @VideoCaption extends Subview
           max = index - 1
         if time >= @start[index]
           min = index
-
       return min
 
   play: ->
+    if @loaded
       @renderCaption() unless @rendered
       @playing = true
 
   pause: ->
+    if @loaded
       @playing = false
 
   updatePlayTime: (time) ->
+    if @loaded
       # This 250ms offset is required to match the video speed
       time = Math.round(Time.convert(time, @currentSpeed, '1.0') * 1000 + 250)
       newIndex = @search time