如何获取embed的当前播放进度?

Question

<embed id="mp1" src="G:\mp3\何洁 希望.wma" align="baseline" border="0" width="350" height="68"
        type="application/x-mplayer2"
        pluginspage="http://www.microsoft.com/isapi/redir.dll?prd=windows&amp;sbp=mediaplayer&amp;ar=media&amp;sba=plugin&amp;"
        name="MediaPlayer" showcontrols="1" showpositioncontrols="0"
        showaudiocontrols="1" showtracker="1" showdisplay="0"
        showstatusbar="1"
        autosize="0"
        showgotobar="0" showcaptioning="0" autostart="1" autorewind="0"
        animationatstart="0" transparentatstart="0" allowscan="1"
        enablecontextmenu="1" clicktoplay="0" 
        defaultframe="datawindow" invokeurls="0">
    </embed>    <script>
        function getPlayTimed(){                
             var timed=mp1.CurrentPosition+"";        
            var arraySp=timed.split(".");            
            if(arraySp[0]==60)
                alert('1分钟');
            else if(arraySp[0]==90)
                alert('1分30秒');    
             
            }
            setInterval("getPlayTimed()",1000);        //1秒钟
            
</script>