It only works on sites that have HTML5 video available, and ClickToFlash is able to identify/work with it.
Here's one thing I find (sometimes) works (on some websites.)
-Install "
Media Center" extension (from the same ClickToFlash developer
-In Safari, go to Preferences -> Advanced -> Show Develop menu in menu bar
-When you get to a "Flash only" site, go to the new Develop menu and change the "User Agent" to "Safari iOS 5.1 iPad"
-Refresh the page
SOMETIMES the page will then give you an HTML5 version instead (if that page has a mobile/iOS version being offered) and then the Media Center extension will give you the AirPlay option too, just like CTF would.
Again, this only works if the web page has an HTML5 version for mobile devices. Many obviously don't. But some do.
Hope this helps! Enjoy!