Quick and dirty fix for the Gamekings extractor. It gives an error about
the video_url, but it downloads it now instead of giving a 404 error on
newer Gamekings videos
When trying to download some GameKings videos, not all worked. This was
because not all videos had a "/large"-URL available. The extractor
checks now if the /large URL is available, if it isn't, it tries to get
the normal URL.