判断是否为视频文件

 private static bool IsVideo(HttpPostedFile file)
        {
            bool isVideo = false;
            string fileName = file.FileName;
            IList<string> formateList = new List<string> { 
               "avi","flv","mpg","mpeg","mpe","m1v","m2v","mpv2","mp2v","dat","ts","tp","tpr","pva","pss","mp4","m4v",
                "m4p","m4b","3gp","3gpp","3g2","3gp2","ogg","mov","qt","amr","rm","ram","rmvb","rpm"};
            if (formateList.Contains(fileName.Split('.')[1]))
            {
                isVideo = true;
            }
            return isVideo;
        }