Opera 10.50 has a big change including some CSS3 features and supports HTML5 draft. With HTML5, you can add a video with a tag.
<video src="BigBuckBunny.ogv" poster="BigBuckBunny.png" width="640" height="360" controls="true" type="video/ogg">You need a HTML5 <video> capable browser to view this movie.</video>
You can try it yourself.
http://snapshot.opera.com/resources/BigBuckBunny.html