I respect your opinion but sadly my service just does not work any other way. You don't go to a theater and choose when the projectionist starts the film, or when the actors start playing, or when the musicians start their concert: the venue / director / manager determine that ahead of time. You don't go to a party and choose what music the host plays, though obviously one hopes the host would value your input should you choose to speak for or against a particular set list. -- That is what my service sets out to create: a shared virtual environment where people can experience media, together, in realtime, as opposed to it being a solitary experience.
If useragents remove my ability to start playing content on behalf of my users (who have already agreed to that by clicking past the event banner) then my service will have to move to a non-web platform. Though we have a difference of opinion hopefully you can see why I find that prospect to be distressing: I love the web, and I hate to see it effectively sunsetting my application.