Download and install (
or re-install even if you already had them) the latest versions, suitable for your flavor of Mac, of:
RealPlayer 11.1 for Mac from:
http://www.versiontracker.com/dyn/moreinfo/macosx/15540
flv files are Flash files.
The latest version of Adobe FlashPlayer can be obtained from here:
http://www.adobe.com/shockwave/download/download.cgi?P1ProdVersion=ShockwaveFlash
(You can check here:
http://www.adobe.com/products/flash/about/ to see which version you should install for your Mac and OS.
You should first uninstall any previous version of Flash Player, using the uninstaller from here (make sure you use the correct one!):
http://kb.adobe.com/selfservice/viewContent.do?externalId=tn_14157
and also that you follow the instructions closely, such as closing ALL applications first before installing. You
must also carry out a permission repair after installing anything from Adobe.