视频播放

为什么我上传的视频（MP4 3GP.....）都不播放，只播放FLV格式的，这是怎么回事？UpFiles文件夹是要保存你上传的文件，PlayFiles文件夹是用于你转换后保存的文件（用于网上播放） 
  ImgFile文件夹是保存截取视频文件的图片，然后那两个mencoder和ffmpeg文件夹是视频转换工具. 
 代码如下：
        string upFileName = "";
        if (this.FileUpload1.HasFile)
        {            string fileName = PublicMethod.GetFileName(this.FileUpload1.FileName);// GetFileName();            upFileName = Server.MapPath(PublicMethod.upFile + fileName);
            this.FileUpload1.SaveAs(upFileName);
            string saveName = DateTime.Now.ToString("yyyyMMddHHmmssffff");
            string playFile = Server.MapPath(PublicMethod.playFile + saveName);
            string imgFile = Server.MapPath(PublicMethod.imgFile + saveName);
            //System.IO.File.Copy(Server.MapPath(PublicMethod.playFile + "00000002.jpg"), Server.MapPath(PublicMethod.imgFile+"aa.jpg"));
            PublicMethod pm = new PublicMethod();
            string m_strExtension = PublicMethod.GetExtension(this.FileUpload1.PostedFile.FileName).ToLower();
            if (m_strExtension == "flv")
            {//直接拷贝到播放文件夹下
                System.IO.File.Copy(upFileName, playFile + ".flv");
                pm.CatchImg(upFileName, imgFile);
            }
            if (m_strExtension == "3gp")
            {//直接拷贝到播放文件夹下
                System.IO.File.Copy(upFileName, playFile + ".3gp");
                pm.CatchImg(upFileName, imgFile);
            }
            if (m_strExtension == "mp4")
            {//直接拷贝到播放文件夹下
                System.IO.File.Copy(upFileName, playFile + ".mp4");
                pm.CatchImg(upFileName, imgFile);
            }
            string Extension = CheckExtension(m_strExtension);
            if (Extension == "ffmpeg")
            {
                pm.ChangeFilePhy(upFileName, playFile, imgFile);
            }
            else if (Extension == "mencoder")
            {
                pm.MChangeFilePhy(upFileName, playFile, imgFile);
            }
            string[] url = playFile.Split('\\');
            TB_userBLL bll = new TB_userBLL();
            TB_sp sp = new TB_sp();
            sp.s_name = url[6] + "/" + url[7] + "/" + url[8] + "." + m_strExtension;//  
            if (m_strExtension == "flv")
            {
                bll.ADDSp(sp);
                Response.Write("<script>alert('上传flv视频成功！');location.href('spManager.aspx')</script>");
            }
            else if (m_strExtension == "3gp")
            {
                bll.ADDSp(sp);
                Response.Write("<script>alert('上传3gp视频成功！');location.href('spManager.aspx')</script>");
            }
            else if (m_strExtension == "mp4")
            {
                bll.ADDSp(sp);
                Response.Write("<script>alert('上传mp4视频成功！');location.href('spManager.aspx')</script>");
            }
            else
            {
                Response.Write("<script>alert('上传有误！');location.href('spManager.aspx')</script>");
            }