Flash Streaming - Video with sound but without image

If you are missing image in our Flash streaming videos, but you can here sound, it means you are using old version of Flash player without support for latest video codec.
They key is to uninstall all references to Flash Player - here is tool to do it:  http://www.adobe.com/cfusion/knowledgebase/index.cfm?id=tn_14157 (version for MacOS and Windows)

Then you can install fresh latest version of plugin from  http://www.adobe.com/products/flashplayer/

Also you might try clearin your Temporary Internet Files cache (Control Panel | Internet Options | General | Delete Files and then check the box to delete all offline content and then Apply and OK out) or Mozilla Cache (Tools / Clear Private Data and keep only cache checked).