In my Safari 5.1.10, Flash content automatically begins playing when a page containing it loads...no pop-ups or locks with which to set prefs...presumably why ClickToFlash has been developed.
Click-to-Plugin (and the special case Click-to-Flash) were developed to stop browser plugins from activating immediately, because of increasingly frequent security risks due to unpatched flaws. Blocking Autoplay was a side effect, and one that in fact is circumvented in current OSes/browser versions (e.g., see Macworld videos) with JavaScript, regardless of CtP or CtF settings. In those cases, blocking Javascript blocks the video autoplay.
