Just to make sure..we're talking about Flash movies in Browsers, not any saved FLVs or SWFs, right?
Windows can't play FLVs when "fresh out of the box"
That it doesn't work in IE could be due to Security levels that need to be adapted:
In IE go to Internet Options, Security tab, then click Custom level. Scroll down until you see where it says "Display video and animation on a webpage that does not use external media player.
" Change it to Enable.
Thanks for the help but it doesn'thelp me if I want to play flash videos does it.
Well it does help if you'd actually read it
Like checking HERE
if your Flash player really installed ok ( I've seen those POS failing more than once
Also are several FF plugins known to interfere with flash videos.
Adblock, NoScript YouTube Downloader only to name a few