The best way is to wrap your video embed tag with div tags.
Then style the div tag so it is where you want.
<div style="text-align: center">
<object id='mediaPlayer' data="Video/hayabusa-turbo-wheelie.wmv" standby='Loading Microsoft Windows Media Player components...' type='type="video/x-ms-wmv"'>
<param name='fileName' value="http://www.johneva.playingwithpsp.com/Video/hayabusa-turbo-wheelie.wmv" />
<param name='animationatStart' value='true' />
<param name='transparentatStart' value='true' />
<param name='autoStart' value="true" />
<param name='showControls' value="true" />
<param name='loop' value="true" />
</object>
</div>
Just remove the
style="text-align: center"
if you want to have the styles in a seperate CSS file(best way) or in the head of your doc.
If you are not using CSS and are not bothered about it being valid you could just use the <center></center> tags(bad way).