I've been playing around with the HTML5 video tag and I'm puzzled as to how best to degrade when you can't support a codec?
For older browsers (or IE) that don't support the video tag at all this quite is straight forward:
<video width="320" height="240">
<source src="vid.ogv" type='video/ogg'>
<source src="vid.mp4" type='video/mp4'>
<object>
<!-- Embed Flash video here to play mp4 -->
<object>
</video>
They will fall through and will receive the Flash version (or other alternate such as an image!)
How about when the browser does support the tag but not the codec - Like FireFox 3.5 for example - and I can't support OGG (possibly because I already have vast archives of H.264):
<video width="320" height="240">
<source src="vid.mp4" type='video/mp4'>
<object>
<!-- Embed Flash video here to play mp4 -->
<object>
</video>
All I get in FireFox 3.5 is a grey box with an x in it. This isn't exactly a great user experience for FireFox users! I can only think of using JavaScript to check for FF3.5 and change the DOM!! is this really the bad old all over again! ...or is there some part of the spec I'm missing out on like a 'novideo' tag?