The users have two modes to choose to block the auto play of the embedded media. First one is disable only the auto play of the embedded media. In this case, the media file will still be loaded and embedded when page is loading. Press the Play button of the controller when you want.
Secondly, users can block the media when loading a page. It will be replaced by a red frame with a play button in the center. Click in the red frame to load and then play it.
For the flash media contents the extension ‘Stop Autoplay’ can: Allow all Flash media, Block all Flash media (and replace it by a blue frame) or block Flash according to the blacklist, which is customized.
Stop Autoplay also provides a whitelist. You can input the keywords of the sites which you allow the auto play.