Behaviour fixed when YT  is not returning a single result/video

git-svn-id: https://plugins.svn.wordpress.org/related-youtube-videos/trunk@852444 b8457f37-d9ea-0310-8a92-e5e31aec5664
v1.5.6

git-svn-id: https://plugins.svn.wordpress.org/related-youtube-videos/trunk@852445 b8457f37-d9ea-0310-8a92-e5e31aec5664