abtx on "HTML5 Video in WordPress"

<video width="100%" height="100%">
<source src="<?php echo $video_mp4; ?>" type="video/mp4">
</video>

Hi,
Above code outputs url as html value instead of rendering actual media file. $video is media file url fetched from custom field. it's a correct url leading to the file and the file plays in the browser.
Why is Wordpress ignoring video tags?

Thanks