@devu what's really going on is the fact that most of the requirements of these sites to require FP 10,0,0,0 or higher is a false claim in most parts. Not unless you start to use specific parts of publishing to FP 10.x - such as the newer 3D routines and perhaps the newer FLV encoding do you truly require a FP 10.1 plugin.

I remember a site I had done in FP 8 about two years ago and the people redid the website and via SWFObject made the site require FP10 when they hadn't touched the *.swf nor *.flv's at all.

That is what you're seeing. The moment that things come in such as signed/certificate signed material that requires FP 10 via Flash Media Server or via Flex 4 SDK or Flash CS5; that's when this trick will start to fully fail.

But YouTube, Facebook and even Vimeo don't really require FP 10. The adoption rate of FP 10 allows them to exclude prior iterations of the flash player because most folks upgrade due to security concerns or because it's automatically updated for them.

That supports my rant against other Flash developers. They need to deploy to the level that the features they require are needed. And if it's VP6 encoding, then that's just Flash Player 8. If it's the new 3D stuff, then it's FP 10. If it's h.264 encoded video, then FP 9. If it's AS3 using the newer Spark or fx.namespace, then it's 10.1 (via Flex).