网站的视频在不同的浏览器中以不同的尺寸显示

Question

这是网站。

http://www.allinonewebshop.co.uk/

主页视频在Chrome，Firefox和Internet Explorer中以不同的尺寸显示。我该怎么办？

谢谢

<p style="text-align: center;"><object width="500" height="300" classid="clsid:d27cdb6e-ae6d-11cf-96b8-444553540000" codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=6,0,40,0"><param name="allowFullScreen" value="true" /><param name="allowscriptaccess" value="always" /><param name="src" value="//www.youtube.com/v/dTcUOPYCwD0?version=3&amp;hl=en_GB" /><param name="allowfullscreen" value="true" /><embed width="500" height="300" type="application/x-shockwave-flash" src="//www.youtube.com/v/dTcUOPYCwD0?version=3&amp;hl=en_GB" allowFullScreen="true" allowscriptaccess="always" allowfullscreen="true" /></object></p>