failed to open source

If the plugin is not set to "Ask" for "Max video quality" in the settings, play back fails with
 XFILE::CFileCache::Open - failed to open source
This is due to the user agent being added to the video_url
failed to open source

If the plugin is not set to "Ask" for "Max video quality" in the settings, play back fails with
XFILE::CFileCache::Open - failed to open source
This is due to the user agent being added to the video_url incorrectly
Merge pull request #2 from m-hume/patch-1

failed to open source