Videos not playing in Safari or Firefox

Hi all.

I can't play some videos in Snow Leopard from either Safari or Firefox. It seems to be related to wmv files, even though I have the latest version of Flip4mac (2.3.0.14) enabled. Basically videos from this website ( http://envoye-special.france2.fr/index-fr.php?page=reportage-bonus&id_article=59) don't play at all. When I click on play in the browser, it says "buffering…", but nothing happens even after waiting a while. The buttons don't even show in Firefox. Stranger still, I can't play the ads on the Apple website using Safari, whereas it works fine in Firefox. Likewise, if I try to watch the news on this French website (www.bfmtv.com), I can play the videos in Firefox, but not the live stream (Le Direct) and none work in Safari.

I have tried everything I could think of like updating all my software, disabling Pithhelmet, making sure Java and JavaScript are enabled, updating Perian, booting in 32 and 64 bits, but it doesn't seem to make any difference. I have also noticed that I have QuickTime player 7 and X installed on my computer and wonder whether there may be some conflict with Flip4Mac. Any suggestions? Your help would be greatly appreciated. Thanks.