Use subtitle URL provided by server rather than generating our own

source/VideoPlayer.brs

@@ -196,10 +196,12 @@ function sortSubtitles(id as string, MediaStreams)
   prefered_lang = m.user.Configuration.SubtitleLanguagePreference
   for each stream in MediaStreams
     if stream.type = "Subtitle" then
-      'Documentation lists that srt, ttml, and dfxp can be sideloaded but only srt was working in my testing,
-      'forcing srt for all text subtitles
-      url = Substitute("{0}/Videos/{1}/{2}/Subtitles/{3}/0/", get_url(), dashedid, id, stream.index.tostr())
-      url = url + Substitute("Stream.srt?api_key={0}", get_setting("active_user"))
+
+      url = ""
+      if(stream.DeliveryUrl <> invalid) then
+        url = buildURL(stream.DeliveryUrl)
+      end if
+
       stream = {
         "Track": { "Language" : stream.language, "Description": stream.displaytitle , "TrackName": url },
         "IsTextSubtitleStream": stream.IsTextSubtitleStream,