-b 500000
is 500kbps for example. There's a ton of options of course, but I generally get good results without much tinkering. This is a good place to start if you're looking for more options: video options.<embed src='{url}' type='application/x-mplayer2' autostart='1' ShowStatusBar='-1' mediawrapchecked='true' width='362' height='288'>
document.getElementById('MediaPlayer').stop();