I don't have IE10 installed, however, according to caniuseit, mp4 is supported in IE9 and 10.
The following html works for me in IE9 & Chrome, note your video file must be in the same folder as your html page on the server (in this example).
<!DOCTYPE html>
<html>
<body>
<video src="abc.mp4" width="640" height="480" preload controls></video>
</body>
</html>
Edit: I have installed IE10 and can confirm the above works there too.
Edit: Since Firefox does not support mp4, and older browsers do not support video natively at all, it is better to provide multiple sources (formats), and fall back, usually to a flash player.
<!DOCTYPE html>
<html>
<body>
<video width="640" height="480" preload controls>
<!-- mp4 supported by Chrome & IE9/10 -->
<source src="abc.mp4" type="video/mp4"></source>
<!-- webm supported by Firefox -->
<source src="abc.webm" type="video/webm"></source>
<!-- last element in video is fall back for native video support, usually a flash player -->
<object type="application/x-shockwave-flash ...>
<!-- last element flash player is usual fall back for flash support, usually some "not supported text" -->
<div>
Your browser does not natively support flash and you do not have flast installed.
</div>
</object>
</video>
</body>
</html>