如果视频的md5为空的话，还是去下载视频吧

git-svn-id: https://plugins.svn.wordpress.org/wp2pcs/trunk@1043977 b8457f37-d9ea-0310-8a92-e5e31aec5664
修复了一些小bug

git-svn-id: https://plugins.svn.wordpress.org/wp2pcs/trunk@1043978 b8457f37-d9ea-0310-8a92-e5e31aec5664