There are many things it could be, but I might start by installing a fresh version of Flash from
http://get.adobe.com/flashplayer/.
That alone may fix the problem. If not, you can try Quicktime instead. We support both formats. Quicktime can be downloaded at
http://www.apple.com/quicktime/download/. Note that you will need to go to your My BDC user settings and switch your video viewing preference to Quicktime.
I also recommend switching to the Google Chrome browser (not just for our website, but all around). Most Windows 8 problems with our website come down to Internet Explorer, which can be fixed if you try hard enough, but typically it's much easier to use a different browser. You can download Chrome here:
https://www.google.com/intl/en/chrome/browser/.
Regards,
Jonathan Atkinson
www.ballroomdancers.com