User should be able to Globally configure whether to disable autostart on Video/Audio tag. This also means [video].play() is disabled from script. if script not started by click event, just we disable window.open() in scripts from non click events. Additionally if a PER WEB SITE Enable/Disable can be done, then it will be cool.
There's a pref to globally disable autoplay now: media.autoplay.enabled, implemented in bug 478982. Can you please either morph this bug (including bug title) into something covering the other items, or close it as fixed?
We can disable autoplay with the pref Matthew pointed out, and we can consider blocking video.play() in future if abuse becomes a problem.
(In reply to comment #2) > blocking video.play() in future if abuse becomes a problem. I dont think waiting to see abuse is a good idea. Then it will become a compatibility issue on many site. I cant see this as WFM, I see WONTFIX as better status for this.