The video ohere Halo: A-Z Posted by halosuperfan117 on January 21, 2012 does appear and play for me. I believe you could have either a browser issue or a Flash issue.
Are you using http:// or https:// see http://en.support.wordpress.com/https/ Try the opposite.
Eaxctly which browser and version of it are you using?
Have you tried clearing your browser cache and cookies?
Is your browser version up to date? You can upgrade any browser version here.
Have you tried using the browser with all extensions or add-ons disabled?
Do you have third party cookies enabled?
Do you have another browser you can try?
You can use this link to see if your Flash is up to date. http://www.adobe.com/software/flash/about/ If it’s not up to date then this is where to download and install the latest version of Flash. http://www.adobe.com/products/flashplayer/