Do you have JavaScript enabled on your windows datacenter IE8 ?
IE9 on windows 7 should use the HTML solution and not care about the Flash...
Are you sure it was not Windows Server 2008?
It appears that windows has a problem and it depends on the order that you install stuff whether the HTML5 Media works in IE9 or not. I know this to be true for Win Server 2008, but as many people seem to report similar, it could affect other windows installs too.
There are details about it hidden away somewhere in this group... I will see if I can find it...
Found it. Here is the post that led to the bug fix in jPlayer.
https://groups.google.com/d/topic/jplayer/2cG56iT2giM/discussionBasically the Flash is used when this error on IE9 is encountered. Which is why I started talking about all this in the first place... As IE9 should have used the HTML5 Media solution for the demo you indicated.