Since the upgrade discussed here the videos haven't been showing correctly.
Unfortunately, I did not do a controlled test/upgrade. I actually upgraded the “flv-embed” plugin around the same time and since these upgrades, the videos have not been showing in any browser.
This is separate to the issue of any page with articles containing videos not displaying for Internet Explorer as discussed separately here.
I am quite a fan of the videos, so I will be trying to get this one up and running quickly. I may change the video player that may ultimately change the way the videos are displayed on the site. Formatting-wise, it may not look visually compliant with the rest of the website.
It seems to have worked after I reinstalled flv-embed manually.
Previous upgrade was with the new Wordpress 2.5.0 "autoupgrade" feature. It would seem that the process didn't complete properly or the files within were corrupted.
This did not change (fix) the Internet Explorer problem though.