Today's limitations of HTML5 video support
It's hard to believe but there are still some.
At least two conditions/limitation when your browser will not play HTML5 video, EVEN if you think you have a decent one:
1. Safari for Windows only supports HTML 5 video if Quicktime is also installed.
2. No support in Internet Explorer prior version 9. (Probably it's not an issue, unless you are inside of corporate network and extremely conservative IT department.)
My test page for you (created by Easy HTML5 Video Converter) to test HTML5 support in your browser. If your browser supports HTML5 video it will play: http://files.kardash.net/jslab/html5video/
Below are links about HTML5 video to consider:
http://www.808.dk/?code-html-5-video - HTML 5 video with table of browsers compatibility.
http://easyhtml5video.com/ - converter of your video format to any of HTML5 supported formats: OGG (Theora video codec), MP4 (H.264 video codec), WebM (VP8 video codec), and Flash MP4 (for fallback to Flash if HTML5 video is not supported).
https://developer.mozilla.org/en-US/docs/Media_formats_supported_by_the_audio_and_video_elements - Media formats supported by the HTML audio and video elements.