meter: 给视频添加标签

[billie66]

参考下面两个问题的答案

http://stackoverflow.com/questions/8455685/how-to-implement-post-tags-in-mongo

http://stackoverflow.com/questions/4976567/get-a-list-of-all-unique-tags-in-mongodb/4977057#4977057

[billie66]

peter 说不给视频加标签了