Youtube videos not playing!

Since the last month or so, all videos on youtube are not playing on any browser that I use (I've used them all). This includes all videos shared from youtube on facebook and other sites like metacafe as well. Whereas all other non-youtube videos, like those purely from metacafe and dailymotion etc, or those uploaded on facebook are playing perfectly well. In short, the problem is with youtube alone and not with any other flash sites. And I update my Adobe Flash player regularly. But I can play the youtube videos perfectly through a software called Free FLV Converter, that has a search, preview and download option from all the major tube sites. Please help. Not being able to watch youtube videos is making me crazy!!!